This Captured Lightning® sculpture was created by injecting a polished block
of acrylic with a beam of high speed electrons from a 5
million volt particle accelerator. Electrons were first
injected from the left side, the specimen was rotated 180 degrees,
and additional electrons were injected through the opposite side. This created two
independent layers of electrical charge, each located about one-half inch below
the surface. The internal charge layer on the right side was then
manually discharged, creating a flash of miniature "lightning" within the
charge layer above. Additional electrical discharges then grew between
the right and left charge layers, forming a beautifully interconnected and complex
3D discharge structure. The
entire discharge took place in less than 100 billionths of a second! The
sculpture is illuminated from below by blue light emitting diodes
(LED's). Each of our Captured Lightning sculptures contains an incredibly detailed, fractal discharge
pattern. Unlike laser art, every one of our sculptures is truly unique. As they
branch, the discharge channels become increasingly finer and hair-like,
ultimately disappearing at the tips. The smallest discharges are
thought to extend down to the molecular level. See our Frequently Asked Questions (FAQ) for a quick overview of how these beautiful objects are created.
(Actual size: 3 x 3 x 2 inches)
What are Lichtenberg figures?
"Lichtenberg figures" are branching, tree-like or fern-like patterns that
are created by high voltage discharges passing along the surface, or inside of,
electrical insulating materials (dielectrics).
The first Lichtenberg figures were actually 2-dimensional "dust figures"
formed as dust in the air settled on the surface of electrically-charged
plates of resin in the laboratory of their discoverer, German
physicist Georg Christoph Lichtenberg
(1742-1799). Professor Lichtenberg made this observation in 1777,
demonstrating the phenomenon to his physics students and peers. He
reported his findings in
his memoir (in Latin): De Nova Methodo Naturam Ac Motum Fluidi Electrici Investigandi (Göttinger
Commentarii, Göttingen, 1777). The translated title of
Lichtenberg's paper is, "Concerning the New Method Of Investigating the
Nature and Movement of Electric Fluid". The physical principles involved
in forming Lichtenberg figures eventually evolved to become the
modern-day science of plasma physics.
Lichtenberg used high-voltage electrostatic devices to electrically charge
the surfaces of various insulating materials such as resin, glass, or
rubber). He then sprinkled a mixture of finely powdered sulfur and
minium (red lead/lead tetroxide) onto the surface. He discovered that
sulfur (being slightly negatively-charged through friction with its
container) was attracted to the
positively-charged regions. Frictionally-charged red lead powder was
found to be attracted to negatively-charged regions. The colored powders
hidden regions of stranded surface charge, and their polarity, clearly visible. Charged regions on the insulator surface were deposited by small discharges of static electricity. It is now known that, once deposited, electrically charged regions often persist on the surface of electrical insulators since the charges are prevented from freely moving and dissipating. Lichtenberg
found that the shapes of positively and negatively charged figures were
significantly different. Positive figures tended to be star-like with
long, multiply-branched paths, while negative figures tend to be shorter, rounded, and
fan or shell-shaped. By
carefully pressing a piece of paper onto the dusted surface, Lichtenberg was
able to transfer these images onto the paper, demonstrating what
eventually became the modern processes of xerography and laser printing. Drawings of some positive and
negative figures that Lichtenberg created are shown below.
Positive Lichtenberg figure
Negative Lichtenberg figure
number of other physicists and experimenters investigated Lichtenberg's
figures over the next two hundred years. Notable 19th and 20th century
researchers included physicists Gaston Planté and Peter T. Riess (mid-1850's), French artist and scientist Etienne Leopold Trouvelot, Thomas Burton Kinraide (late 1800's), and professors Carl Edward Magnusson, Maximilien Toepler, P. O. Pedersen, and Arthur Von Hippel
(1920's-30's). Modern researchers often used photographic film to
capture the faint light emitted by the positive or negative high voltage
discharges. An English industrialist and
electricity researcher, Lord William G. Armstrong of Cragside,
published two very beautiful full-color books (now quite scarce!) showing some of the results of his high
voltage and Lichtenberg Figure research. Fortunately, a copy of his
first book, "Electric Movement in Air and Water, with Theoretical Inferences", was recently made available through the kind efforts of Jeff Behary at the Turn of the Century Electrotherapy Museum. In the mid-1920's, Von Hippel discovered that
Lichtenberg figures were actually created through complex interactions
between ionized gas (corona discharges
and small electrical sparks called streamers) and the
underlying dielectric surface. The discharges deposited matching patterns
of electrical charge onto the dielectric surface below, where they became temporarily stranded. Von Hippel also
discovered that increasing the applied
voltage, or reducing the surrounding gas pressure, caused the length of
the figures to increase.
relationship between the length of Lichtenberg figures versus voltage
was utilized to create early high voltage recording instruments, such
as the klydonograph. Riess discovered that the diameter of a positive figure
was about 2.8 times the diameter of an equal-voltage negative figure. These
properties were later used to measure the peak voltage and polarity of lightning strikes.
Klydonographs photographically recorded the size
and shape of Lichtenberg figures that were created by abnormal
on electrical power lines created by nearby and direct lightning
strikes. These allowed lightning
researchers and power system designers in the 1930's and 1940's to
measure lightning-induced voltages and
polarities, thus providing critical
information about the electrical characteristics of lightning strikes.
This information was essential so that power engineers could create
"man-made lightning" and then test the effectiveness of
various lightning-protection approaches in high voltage laboratories.
Lightning protection is now a critical part of the design for modern
transmission and distribution systems. A schematic diagram of the
main parts of a klydonograph is shown on the leftmost drawing below,
examples of "klydonograms" from equal magnitude positive and negative
high voltage transients. Notice how the positive Lichtenberg figure is
much longer than the negative figure even though the peak voltage is of the same magnitude.
Schematic view of a klydonograph showing the position of the
photographic film and high voltage electrode. Light from the high
voltage discharges creates a photographic record of the event.
From W.W. Lewis, "The Protection of Transmission Systems
Against Lightning", John Wiley & Sons, 1950
Lichtenberg figures are now known to occur during electrical breakdown
within many gases, insulating liquids, and solid dielectrics.
Lichtenberg figures may be created within billionths of a second (nanoseconds)
when dielectrics are subjected to very high electrical stress, or they may develop over
a period of many years through a progressive series of small, low-energy, partial discharges.
Countless partial discharges on the surface or interior of solid
dielectrics often create growing, partially-conductive 2D surface
Lichtenberg figures and internal 3D "electrical trees".
trees are often seen along the surfaces of contaminated power line
insulators, and they can also form, hidden from view, inside dielectrics
due to the presence of small internal defects or voids, or at points
insulator has been physically damaged. Since these will eventually cause
complete electrical failure of the insulator, preventing
their initial formation and growth is critical to the long-term reliability of
3D Lichtenberg figures were first created inside transparent plastic by
physicists Arno Brasch and Fritz Lange in the late 1940's. By using
their newly-invented electron accelerator, they injected huge numbers
of free electrons into plastic specimens, causing electrical breakdown and the formation of carbonized internal Lichtenberg figures. Electrons
are tiny, negatively charged particles that orbit the positively-charged nucleus of the atoms that make up all condensed matter. At
their laboratory at AEG (Berlin, Germany), they used high voltage pulses from a multi-million volt Marx Generator
to drive a pulsed electron beam accelerator. An
article about their research and their accelerator (which they called a
"Capacitron") originally appeared in the March 10, 1947 issue of LIFE
The Capacitron could deliver a three-million volt pulse, and could
generate a powerful beam of free electrons with a peak current of
up to 100,000 amperes! The glowing region of ionized air created by the
beam of electrons resembled a bluish-violet rocket engine flame. A complete set of previously unpublished B&W pictures,
including Lichtenberg figures inside a clear block of plastic, has
recently become available online, as has another article with color pictures from the April, 1951 issue of Popular Mechanics.
The formal scientific study of trapped charges and their behavior within
dielectrics was first conducted by the Brazilian physicist, Dr.
Bernhard Gross, in the early 1950's. Dr. Gross confirmed that internal Lichtenberg figures could be created within a variety of polymers and glasses by injecting them with high-energy electrons using a linear accelerator (LINAC).
The techniques that we use to make our sculptures are built upon
the theoretical work and techniques originally developed by Gross,
Brasch, and Lange. These 3D Lichtenberg figures are sometimes
called electron trees, or beam trees. We call oursCaptured Lightning® sculptures.
How do we make our Captured Lightning® sculptures?
Over many years, we have refined irradiation and fabrication
techniques to create a wide variety of beautiful 2D and 3D sculptures.
We start with carefully cut and polished shapes made from a clear, glassy polymer called polymethyl methacrylate (or PMMA).
This material, commonly known as "acrylic", is sold under various trade
names such as
Lucite, Plexiglas, or Perspex. PMMA has a unique combination of
high optical clarity and superior electrical
and mechanical properties. Besides being an excellent electrical insulator,
it's also clearer than glass! A number of other clear polymers, such
(PC), polystyrene (PS) , polyethylene terephthalate (PET), and polyvinyl
chloride (PVC) can also be used to make Lichtenberg figures with varying
degrees of success. However, most of
these other materials tend to form dark gray or black discharge patterns instead
of the sparkling,
mirror-like figures seen within PMMA. Lichtenberg figures can also be
created within glass. However, glass Lichtenberg figures may shatter upon discharge or (unpredictably!) some time later, so we no longer make them.
We inject electrons into our specimens using a 150 kW particle accelerator called a Dynamitron.
The heart of this device is the accelerator tube - a huge four-story high
evacuated "vacuum tube" that operates at voltages between one and
five million volts. At the top of the tube, electrons are emitted by a
small, white-hot tungsten filament. The filament is also connected to the negative output terminal of a
multimillion volt power supply, while the bottom of the tube is connected to ground and the positive terminal
of the high voltage power supply. This configuration creates a very strong
field that accelerates electrons emitted from the filament to a very
high velocity as they "fall" though the large potential difference
towards ground. The
bottom of the vacuum tube has very thin (only 2.3 thousandths of an inch thick!) titanium
window that separates the high vacuum on the inside
from air, at atmospheric pressure, on the outside. The high velocity electrons pass right through
the titanium window, almost as though it wasn't even there! The electrons then emerge
from the outside surface of the window, and then travel another 18 inches of air before
crashing into our acrylic specimens on the movable carts below. Although the average lifetime of free electrons in
air is only 11 billionths of a second, that's more than enough
for them to work their magic inside the acrylic specimens below.
The energy of electrons leaving the accelerator is measured in millions of electron volts (or MeV).
Most of our sculptures were created using electrons with energies
between 2 - 5 MeV. At these energies, the electrons are traveling at relativistic velocities - between 98.5% and 99.6% of the speed of light. During irradiation,
the speedy electrons are driven deep inside the
acrylic before coming to a stop. The penetration depth is a function of
the energy of the electron beam, the target material's
dielectric properties, and its atomic density. The higher the energy of
the electron beam, the deeper the electrons
will penetrate. For example, electrons with an energy of five MeV will
penetrate about one half of an inch into PMMA, but a sheet of lead only
1/16" thick will completely stop them.
a thick specimen is irradiated, huge numbers of electrons
accumulate inside, creating a strongly-charged cloud-like
layer called a space charge.
Because PMMA is an excellent electrical insulator, injected electrons
become temporarily trapped deep inside. By passing
specimens through the electron beam in two or more passes (changing
specimen orientation between passes), or by rotating
specimens while they're being
irradiated, complex 3-dimensional regions of space charge can be
Under continued irradiation, electrical charges accumulate and the electrical stress inside the acrylic dramatically
increases. The electrical stress (E-field) and may reach many millions of volts per centimeter. We normally
our specimens just below the point where they'll self-discharge.
Because the acrylic is an excellent insulator, the excess charges cannot escape, and the carts
transport the fully-charged specimens out of the accelerator. We then
force the specimens to discharge by poking them with heavily-insulated,
metal tools. The small divot creates a tiny region where the electrical stress overcomes the
dielectric strength of the acrylic. The increased electrical stress breaks the chemical
bonds that hold the acrylic molecules together, stripping away free electrons in a process
The newly-freed electrons are then accelerated by the
extreme electric field, and these collide with, and ionize, more acrylic
molecules. Portions of the acrylic abruptly become electrically
conductive in a runaway process called avalanche breakdown.
billionths of a second, a network of branching, conductive channels form within
the acrylic as, with a bright flash and a loud BANG, the
material suddenly undergoes dielectric breakdown.
The previously-trapped electrical charges rush out in a river-like
torrent as thousands of smaller branches dump their
share of charge into larger channels, eventually merging into a
single, brilliant discharge path that exits the acrylic. Although it
appears like we're injecting high voltage into the block, we're
actually removing the excess
charges that were previously trapped inside. Dielectric breakdown occurs with incredible speed - the main electrical discharge
within a 4 inch square specimen lasts less than 120
billionths of a second! Some solid state physicists now think that dielectric
breakdown within a charge-injected solid is the most energetic
(explosive) chemical reaction known, vastly exceeding
that of high explosives. The following image shows a 12 x 12 x 1 inch
specimen being discharged. In the image, a neutral density filter
reduced the brilliance of the discharge so that the individual paths could be
seen. Note the bright high-current discharge
jumping along the top surface of the specimen to the grounded
metal table below:
(Photo courtesy of Terry Blake)
the miniature lightning bolts blast their way through the acrylic, they create
millions of microscopic tubes and fractures,
leaving behind a permanent "lightning fossil" deep inside the acrylic. The peak current
within the electrical discharge reaches hundreds, or even thousands of
amperes depending upon the size of the specimen. The hot plasma within
the discharges causes the acrylic to melt and fracture along each path.
Higher-current "roots" may lightly char the surrounding acrylic. The exit point of the
discharge creates a small crater on the surface. Surprisingly, although we inject a huge amount of negative charge into our
specimens, the electrical discharges originate from points which
are more electrically positive (versus the space charge layer), so all of our
Captured Lightning® sculptures are
actually "positive" Lichtenberg figures!
Some specimens may "self-discharge" as they are being irradiated. This
is usually caused by the presence of a small surface
scratch, residual manufacturing stress, or a hidden internal defect. A
self-discharged specimen will continue to discharge numerous times as
irradiation continues. However, unlike the neat branched structures seen
sculptures, self-triggered sculptures develop a mat-like tangle
of chaotic discharges or a complex combination of dendritic and chaotic
patterns. Because of their complexity, self-discharged specimens are
among some of our most fascinating sculptures.
Video of huge 15 x 20 x 2 inch sculpture being discharged:
Following is a
short video clip showing a huge 15" x 20" x 2" specimen being discharged during our 2010 production run.
This specimen was first charged on one surface by a 5 MeV electron beam.
The fully-charged specimen was then (very carefully!) flipped
over and irradiated
once again on the other side. This created two independent charge
planes, each located about
1/2" below the large surfaces. Prior to discharging,
the estimated potential of these internal charge
planes was about 2.6 million volts. Because of the two charge planes
and large size, this specimen stored significantly more
electrostatic energy than most of our other
specimens - over four kilojoules! Safety precautions were necessary to prevent the
possibility of receiving a dangerous electrical shock.
Although the main discharge is very brief (under 500
billionths of a second!), the video successfully captured the brilliance
of the 4 kilo-Joule main discharge in a single video frame (below). Numerous
secondary discharges continued to flash after
the main discharge. These continued sporadically for over 30
minutes. This video is courtesy of Bill Hathaway, GCL
Laboratories. The resulting sculpture, cradled within a custom walnut
light base and
illuminated by an array of white and blue LED's, is also shown below.
(Click on above image for high-resolution image)
The rounded, crystalline flakes that make up the Lichtenberg Figure consist of chains of hollow tubes and tiny conchoidal
(shell-shaped) fractures. Conchoidal fractures are characteristic of the way glassy (amorphous)
materials fracture when stressed beyond their breaking point. The countless
fractures behave as tiny mirrors, so illuminating a figure through an
edge causes the entire Lichtenberg figure to glow brilliantly
with the reflected colors of the external light source.
Lichtenberg figures are fractals
branching patterns of Lichtenberg look
similar at various scales of magnification. This "self-similarity"
strongly suggests that Lichtenberg figures might be mathematically
described through a relatively new branch of mathematics called Fractal Geometry.
Fractal objects do not have integral (2D or 3D) dimensions, but
instead have fractional dimensions. Our branching 2D Lichtenberg figures have a fractal
dimension of about 1.5 (for thin, sparse discharges) to 1.9 for very dense discharges, with most figures averaging about 1.7, and our 3D figures have a fractal dimension of about 2.5. The appearance of Lichtenberg figures depends upon
how much charge was injected into the acrylic and when the
specimens are discharged. Branching figures are technically called
meaning tree-like. If a larger amount of electrical charge is injected
into a specimen, very dense
dendritic discharges can be
created such as in Figure 1 below.
These very dense discharges are similar in appearance to fern fronds
("filiciform") or moss agate. Specimens exhibiting this form were
charged to just below the point of self-breakdown and immediately
discharged. If the level of
electrical charge is reduced, more classical, lightning-like or
tree-like discharges are created (Figure 2). If premature breakdown
occurs as we are
actively irradiating a specimen, a densely tangled mat of "chaotic"
discharges occurs (Figure 3). If the specimen self-discharges as it is
being irradiated, new electrons from the beam cause smaller nearby regions to
recharge and discharge repetitively in
random directions from existing discharge channels. This results in a
thicker, chaotic tangle of discharges that are reminiscent of
interconnected nerve cells and neural networks.
We sometimes get fascinating and complex combinations of these
patterns when a specimen self-discharges about halfway through the charging
Figure 3. Chaotic Discharges
while being irradiated)
of dendritic discharges can easily be seen in the following sequence of
zooms from a 12" x 12"
Lichtenberg Figure. Although the branches become finer and hairlike, the
overall branching structure remains similar until the finest tips ultimately disappear at the very edges of the discharge structure.
Similar fractal patterns are prevalent in nature. They are seen in
aerial views of rivers and their tributaries, and organic structures
such as branching tree limbs, your body's circulatory system, and lung
tissue. The satellite
view below shows the fractal pattern of a river drainage system near
Grand Junction, Colorado, USA. The right image is a casting of the
bronchial tree of a human lung (courtesy Paul Cazeaux, PhD student at
Laboratoire Jacques-Louis Lions (LJLL), Paris, France). These branching structures may be a consequence of a recently proposed law of physics, the Constructal Law, which states that Nature tends to develop a hierarchical branching network of paths that result in most efficient flow. The flowing material can be water, air, electrons, etc.
Lichtenberg figures can be modeled using a process called "Diffusion Limited Aggregation" (DLA). An enhanced model that combines an electric field with DLA is called the Dielectric Breakdown Model (DBM).
The DBM appears to fairly accurately describe the macroscopic branching
forms of electrical breakdown that occur within solid, liquid, and gaseous insulators under diverging electrical fields.
Other interesting properties: fluorescence, solarization, birefringence, and discharge-free zone
acrylic is irradiated by high-energy electrons, it glows brilliantly with a
blue-white color. Radiation chemistry studies suggest that this is mainly due
to luminescence that peaks at a wavelength of about 435 nm. However, acrylic also generates fainter glows from x-ray fluorescence, and Cherenkov radiation.
The exact light-producing mechanisms for electron-irradiated PMMA are not fully
Newly-irradiated specimens develop an amber-colored layer in the
region between the surface(s) that were irradiated by the electron beam and the
discharge layer. The phenomenon is called solarization,
and it appears to be caused by a various interactions between high speed electrons
acrylic's molecular structure. During irradiation, beam electrons are
initially traveling at
about 99% of the speed of light. As they penetrate the specimen, they
collide with acrylic molecules, rapidly coming to a stop within a
fraction of an inch. Electrons in the beam have a tremendous
amount of kinetic energy, and as they suddenly brake to a stop,
they release their kinetic energy in the form of heat and X-radiation. In acrylic, most solarization seems to occur in the regions
directly hit by the
beam of electrons. However, it has recently been found that regions that are intentionally covered by sheet lead
(to prevent electrons from hitting some areas of the acrylic) may also exhibit solarization in deeper regions of the acrylic. As electrons crash into the lead mask, they radiate even more intense X-radiation that appears to create solarization even more deeply within the acrylic underneath the mask. Energetic collisions with electrons, x-rays,
and excess electrons injected into the acrylic's molecular structure apparently
stimulate chemical and physical
reactions that alter the physical and optical
properties of the acrylic. Deeply-trapped excess electrons may remain
for years, creating color centers which also contribute to solarization. While some of these changes last for only minutes or hours, others
persist for months or years. Some changes appear to be
permanent. Although the specific causes of solarization are not completely understood, there
is evidence that irradiation creates unstable, longer-lived
"metastable" compounds that preferentially absorb light at the blue end
of the spectrum (250 - 400 nm). Partial absorption of the blue portion of ambient light causes the solarized regions to
appear green, brownish, or amber when illuminated by white light.
Most of our specimens turn a beautiful lime-green color immediately after
irradiation. At room temperature and after discharging, this fades to amber over the next few
hours. The amber region may
then take months, or even years, to eventually fade away.
Fading can usually be accelerated by gently heating the block in the
presence of oxygen (or air), or by leaving the specimen in sunlight for
extended period of time. As oxygen diffuses into the
acrylic from the outside surfaces and the porous discharge layer, it
slowly bleaches the
solarized region, causing the solarized layer to gradually become
thinner and thinner,
until it eventually disappears. Most older Lichtenberg figures are
Although older specimens may no longer show any solarization, some may exhibit
slight "fogging" due to radiation damage in the acrylic. Some
specimens exhibit little initial solarization, while a small percentage of
specimens permanently retain
their amber color. Permanently colored specimens appear to be solarized
via different, deeper penetrating mechanisms, such as X-radiation, since
these specimens also tend to be uniformly solarized throughout the
instead of a relatively thin layer.
It has also been discovered that the solarization layer is often fluorescent.
An amateur scientist from Australia, Daniel Rutter, discovered that monochromatic light from a green laser pointer changes color
when passed through the solarized layer of a Lichtenberg figure. More
recently, we have discovered that the light from a near-ultraviolet
source (such as a Blu-ray laser or bright blue LED's) also causes
the solarized region to fluoresce with a yellow-green color. Both
effects appear to be due to one (or more) fluorescent components within the
solarization layer. As the solarization fades over time, so does the
Most specimens also exhibit slight changes in the
in the regions near the discharge layer. This is
thought to be due to residual mechanical stresses near the discharge
stresses near the Lichtenberg figures can sometimes be seen as
multicolored regions near the discharge plane when a sculpture is
illuminated by polarized
light and then viewed through a second polarizing filter (a configuration called crossed polarizers). When physically stressed,
acrylic exhibits a property called birefringence.
When viewed through crossed polarizers, stress-induced
birefringence causes changes in color that are directly related to the
amount and distribution of otherwise hidden stresses. An electrically
clearly shows internal compressive forces created by the high electrical
field. These forces are then relieved when the specimen is discharged.
Following are images of the same specimen prior to charging, fully
charged, and then after discharging. Little internal stress is seen in
the initially uncharged specimen. The specimen was then charged by
injecting electrons from the left side. The injected charge forms an
intensely negative layer of charge near the center of the specimen. At
the same time, positive ions are strongly attracted to the external
surfaces of the specimen. partially neutralizing the overall external
charge outside the specimen. Attraction between the internal negative
layer and the positively-charged outer surfaces create significant
compressive stresses within the acrylic. These can easily be seen as
colored regions on either side of the center in the middle image. After
the specimen is discharged, the electrical stresses are greatly relieved
as can be seen in the rightmost image. There are still residual
mechanical stresses near the discharge zone due to fracturing. Click on
any of the individual images to see full-size images.
Initially uncharged specimen
Fully charged specimen
(electrons were injected from left side)
Finally, you'll notice that all of our sculptures have a discharge-free boundary along the outside edges. Because
acrylic is not a perfect insulator, some of the internal charge can leak
away along all the edges. The rate that excess charges can leak away is highest where the internal electrical field is greatest - i.e., in the region
between the edge of the internal space charge region and the perimeter of each
specimen. In these regions, the amount of stored charge is reduced to the point
where it can no longer break down the
acrylic. The result is a discharge-free zone along the perimeter of every specimen.
"Iced 'bergs" and negative Lichtenberg figures:
We have confirmed that fully-charged specimens retain their
injected charge and their initial green color for several weeks
when maintained at dry ice temperatures (-109F/-78.5C). One of our team
members, Todd Johnson, has christened these "Iced
'bergs". At room temperature, the excess charge
trapped within acrylic leaks away with an exponential time constant ranging from a few minutes to
a few hours. Chilling
specimens significantly reduces the speed that free charges can move within the
dramatically reducing the rate that trapped charges can leak away. At dry ice temperatures, trapped charges appear to remain stored indefinitely. Other researchers have stored chilled specimens
for many months, and have discharged them with little, if any, difference from freshly charged specimens! This suggests that the initial green color may be related to the
high density of electrons that remain trapped before discharging.
Once discharged, even chilled specimens rapidly lose their green color, changing to the longer-term amber
We also discovered that chilled specimens develop a layer of frost when
warmed in humid air. When we discharge a specimen, we produce a positive
Lichtenberg figure inside the acrylic. Photographic evidence confirms that the exiting spark "wraps
around" the exterior surfaces of the specimen, discharging the positive charges that were
attached to the outer surfaces of the specimen. The
external surface discharge produces a negative
Lichtenberg figure along the
large surfaces of the specimen. However, negative surface
discharges are considerably fainter than the brilliant positive
internal discharges, so they are normally very difficult to see or photograph.
We accidentally discovered that, if the charged specimen is coated with frost, the discharges along the acrylic surface blast away the frost layer immediately above the discharges, making the paths taken by
the negative discharges clearly visible. As can be seen in the image below, the
resulting negative Lichtenberg figures left in the frost show considerably
branching than positive internal figures... just as professor
Lichtenberg originally observed over 200 years ago. The following "iced
discharged by Todd Johnson and Dr. Tim Koeth during our
2010 production run:
Discharge current measurements... and a paradox During our 2007 and 2009 production runs, we measured and recorded discharge
current waveforms for a number of 4" x 4" x 3/4" specimens. We designed a special holding
fixture with copper foil plates that made physical contact
with the large surfaces of a charged acrylic specimen. A heavily-insulated wire connected the pair
of foil plates to a pointed discharge tool, and this wire was also passed
through the center of a wideband Current Transformer (CT). When the
specimen was discharged, the main current pulse flowed through the wire
and was measured via the CT. The CT
transformed the discharge current pulse
that flowed through the wire into a voltage pulse that could then be
captured and stored within a high speed
Tektronix digital storage oscilloscope. The experimental configuration can be seen below:
One of the digitized waveforms
is shown below. We found that, for this 4" x 4" specimen, the entire main discharge
event occurred in less than 120 billionths of a second (120 ns), the
peak current reached almost 600 amperes in 45 ns, and the waveform contained
four discrete current peaks. Discharges from a number of other specimens showed between three and seven
suggests that propagating electrical trees may progress via a series of
advancing breakdown waves. Each current peak may reflect a surge of newly
conducting channels ("streamers" and "leaders") as they tap into new sources of stored charge. Newer channels
apparently blast their way into previously untapped reservoirs of
charge within the acrylic, pause briefly, then surge again, etc. The
average discharge velocity was between 8.5 x 105 and
1.3 x 106 meters/second (526 and 790 miles/second, or around 0.3% the speed of
light). However, pauses between successive current surges suggest that the peak discharge
velocity during the propagation phases was even faster. Surprisingly,
the average velocity within the specimen was actually 10-100 times faster
than the velocity of positive lightning leaders in air. This is thought to be
due to the extreme electrical field (estimated to be over 20
million volts/cm) at the tips of the propagating discharges within the
The high streamer velocities within PMMA create a paradox, since they are over 800 times the speed of
sound within PMMA. This is completely inconsistent with Griffith's theory of crack propagation within solids,
which predicts that the maximum speed that cracks can propagate within a solid
is limited to the speed of sound within the material, or about 1.6 x 103
meters/second for PMMA. The current waveform
clearly demonstrates that the breakdown process (the complete formation
of chains of cracks and gas channels across the specimen) for our Lichtenberg
figures propagates at speeds that are almost 1000 times
FASTER than the maximum predicted by classical materials
theory! A series of electro-optical measurements were recently made by
Dr. Timothy Koeth in his laboratory at the University of Maryland. Dr.
Koeth measured the time delay between optical (light) emissions at the beginning and ends of
propagating discharges within 6" x 6" x 1" specimens. His measurements showed streamer velocities that ranged between 7.4 x 105 and 1.55 x 106 m/s.
Some insights into this paradox may come from a Russian
researcher, Yu N. Vershinin. Dr. Vershinin explored how electrostatic energy is stored and released within solid
dielectrics. Specifically, he studied how energy is stored within
acrylic when charge is slowly injected (called "charge trapping") and
the effects of rapidly releasing trapped charges ("charge detrapping") when the
dielectric undergoes electrical breakdown. Vershinin proposed
that, when a dielectric contains significant trapped space charge,
the stored electrostatic potential energy is rapidly liberated, contributing to
explosive formation and growth of crack tips. As chemical bonds in the surrounding material are ruptured,
high pressure gases are liberated, expanding the channels behind the
propagating crack tips. Vershinin speculated (and experimentally
confirmed) that for very high internal electrical fields (E-fields), the potential
energy initially stored within the E-field was rapidly converted into
kinetic and thermal energy that drove crack
propagation at hypersonic velocities.
Vershinin found that this occurred only for propagating positive
discharges within highly divergent E-fields. An American researcher, Dr. Paul
Budenstein, has independently developed a theory of dielectric breakdown in solids that
seems to explain many of the observations. Based upon the rate of
channel expansion, Budenstein concludes that dielectric breakdown may be the
most rapid chemical reaction in nature.
Evidence for the above theories of breakdown and discharge propagation can be seen within Captured Lightning Lichtenberg figures. Under high magnification, the discharge channels that make up the figures are found to be hollow tubes, surrounded by countless small fractures that scatter light. Some paths clearly exhibit periodic structures along the discharge channel, similar to beads along a string. These beaded structures are observed during dielectric breakdown of various polymers and crystalline ionic salts. The theories predict that under the extreme electrical field ruptures the chemical bonds within the acrylic. The resulting "electronic breakdown" (or electronic detonation) processes liberate gases as some of the insulating material is decomposed into its atomic constituents. Dr. Koeth has verified that a significant volume of gas exits from the discharge point when a specimen is discharged under water. Other researchers have determined that the evolved gases are composed primarily of hydrogen, carbon monoxide, carbon dioxide, and methane. "Beading" appears to be a
repetitive sequence of electronic decomposition, evolution of gases
under high pressure, and formation of new cracks ahead of the expanding gas zone. Following is an example of a beaded channel captured Bill Hathaway (GCL Laboratories).
detonation is hundreds of times faster than the detonation waves that propagate through even the fastest chemical explosives!
Vershinin termed the explosive breakdown process
"electronic detonation" since it was similar to the way that chemical
reaction shock waves supersonically propagate through a high
explosive as it detonates. Because of the large amount of electrostatic energy stored within our
specimens, and the extremely short discharge intervals, the
instantaneous power liberated during a discharge can
exceed a gigawatt (109 watts)! Not surprisingly, the discharge creates
a loud BANG(!), and the brilliant, blue-white
lightning-like spark channels wreak considerable havoc inside the acrylic as they blast
countless permanent fractures and tubes along the space charge
layers. Charge detrapping is now known to play a profound role in the degradation
and breakdown of solid dielectrics that are subjected to long-term high voltage
stresses, sudden voltage changes, or abrupt polarity reversals. In some
respects, sudden charge detrapping in a solid dielectric is similar
to a high-voltage capacitor discharge that occurs solely within the insulating material.
After we discharge a specimen, hundreds of smaller
secondary electrical discharges continue to flash throughout the
specimen as small pockets of residual stranded charge continue to redistribute
themselves. Large sculptures sparkle and sizzle, making a sound similar to
frying bacon, and intermittent sparking has been seen over 30 minutes after the main discharge.
These harmless secondary discharges often sting our fingers when we handle
recently-discharged specimens. Click on the following image to see some high
resolution video captured during one of our production runs that shows
primary and secondary discharges.
(Photo and video courtesy of Mike Walker and Theodore Gray) Click on the Above image to see a video clip
of many Lichtenberg figures being discharged
Natural Lichtenberg figures - fulgurites, natural tattoos, and fractal lightning
Occasionally, nature creates "fossilized lightning". Called fulgurites,
these are hollow, glass-lined tubes that are formed when the powerful
electrical current from a lightning strike creates underground discharge channels
within poorly-conducting sandy or sandy-clay soils. The intensely hot channels from the lightning arc melt the surrounding sand
and soil particles to form glassy tubes. Larger
fulgurites often exhibit fractal characteristics as they split into
smaller diameter root-like branches at further distances from the site
of the main strike.
Lichtenberg figures, sometimes called "lightning flowers" or "skin feathering", sometimes form
beneath the skin of unfortunate humans who have been struck by lightning. The victim often has one
or more reddish radiating feathery patterns that branch outward from
the entry and exit points of the strike. Here is an example of an electrical tattoo from a lucky lightning survivor:
OUCH! A temporary lightning tattoo on a "lucky" survivor
From "Lichtenberg Figures Due to a Lightning Strike" by Yves Domart, MD, and Emmanuel Garet, MD,
New England Journal of Medicine, Volume 343:1536, November 23, 2000
Medical terms for this phenomenon include arborescent lightning burn, arborescent
(tree-like) erythema, keraunographic markings, or ferning
patterns. Although the exact causes are subject to
some debate, they appear to be the result
of physical damage to capillaries under the skin, perhaps caused
by the flow of electrical current, or by shock wave bruising from external
flashovers just above
the skin. These reddish marks fade away over a
period of hours or days. They are recognized by forensic pathologists as clear evidence
that a victim has been struck by lightning. The patient above survived
with no permanent injuries, and the lightning flowers completely faded
within a few days. A small Lichtenberg figure
has also been observed at the entry point
where a high voltage spark penetrated the skin of an unfortunate (but
surviving) local electrical experimenter who was accidentally zapped by a
homemade 60,000 volt Marx Generator. No... it wasn't me!
A similar phenomenon is sometimes seen when lightning
hits a grassy field, as in this picture where lightning struck a
golf course flagpole, leaving this beautiful 25 foot Lichtenberg figure on the
(From "Lightning and Lichtenberg Figures" by Cherington, Olson and Yarnell, Injury, Volume 34, Issue 5, May 2003)
Note the similarity between the figure above and the Lichtenberg figure below (illuminated from below by blue LED's):
High voltage discharges to the surface of water can also create Lichtenberg figures. Some beautiful examples of
both positive and negative Lichtenberg figures on water surfaces can be seen on Dr. Colin
Pounder's Lichtenberg figures web site. Natural lightning often creates transient "Lichtenberg figures" in the sky. Air is an excellent dielectric and, although the physical breakdown
mechanisms for air and Plexiglas are considerably different, the appearance of the
branching discharges is quite similar. So it should not be surprising that the branching forms of lightning leaders also have fractal
characteristics. This similarity can clearly be observed during "anvil crawler" and horizontal "spider lightning".
Spider lightning follows a thin, positively charged cloud layer, and the
slowly propagating discharges can crawl across the sky for 30-50 miles
- literally spanning from horizon to horizon. On a much smaller scale, transient Lichtenberg figures
(sometimes mistakenly called St. Elmo's Fire) sometimes appear on the outer
surface of cockpit windows of airplanes as they fly through
Similar branching fractal patterns also occur when thunderstorms generate electrically conductive leaders that
propagate downward from a charged cloud to the ground below. When one
of these leaders connects with an unfortunate object on the ground, a high current pulse (called the return stroke) surges back upward through the completed path, resulting in a Cloud-to-Ground (CG) lightning
strike. The peak current is typically tens of thousands of amps, and large positive bolts may reach several hundred thousand amps. Exceptional examples of downward propagating positive leaders have been captured by South Dakota lightning
researcher, Tom Warner. Using high speed video imaging equipment, he
was able to capture the downward progression of leaders and the return
strokes from a positive lightning bolt. Positive lightning
is a significantly rarer, and considerably more dangerous, form of lightning than negative lightning. Tom's "slow motion" videos show the air breaking down, forming
glowing conductive plasma paths (called leaders) that fan
downward from a huge reserve of charge within the cloud
above. The brightly glowing tips of the positive leaders smoothly propagate,
unlike negative leaders which propagate in a series of discrete jumps (called stepped leaders). The
first descending leader to finally connect with the Earth below
completes the circuit, resulting in a powerful Cloud-to-Ground (CG) lightning discharge. See Tom's web site to see his spectacular gallery of images and videos of positive and negative lightning.
Under special conditions lightning also creates transient upward-growing
Lichtenberg figures. This phenomenon often occurs when broadcast
antennas or mountain tops generate positive leaders that propagate
upward into heavily-charged negative regions above. As the ground-based
propagate into the negatively-charged regions, they form a
positive Lichtenberg figure that, except for it's massive scale, looks
quite similar to our Captured Lightning Lichtenberg figures. This
phenomenon has been captured in another slow-motion video by Tom Warner -
click on the following image to see the YouTube clip:
Lichtenberg figures can also be seen at some high energy pulsed
power facilities, especially where deionized water is used as a dielectric to briefly store
large amounts of electrical energy. The following photo is from Sandia National Laboratory's mighty Z
Machine, the world's most powerful electrical pulse generator. After
completion of a high energy experiment, the water breaks down from the
huge electrical stress,
becoming an electrical conductor that safely dissipates unwanted
residual energy from the system. The filamentary breakdown paths form
Lichtenberg figures that dance across
the water's surface. If you look closely, you'll notice that many of the
paths actually trace out high voltage
electrical field lines along the surface of the water. Although
impressive, this display is only dissipating "left over" energy after
the experiment is over. The discharges below represent only a very small
fraction (perhaps 5%) of the initial energy that was used during the
previous pulsed-power experiment.
(Click for a higher resolution 840 x 554 pixel image)
Are there any practical uses for Lichtenberg figures? Analysis
of the form and origination points of Lichtenberg figures is a powerful
tool for diagnosing, and subsequently preventing, high voltage
solid dielectrics. By examining these figures, experts can diagnose and
prevent future electrical faults within a variety of devices, such as
high voltage transformers,
capacitors, and insulators used by electrical utilities. Historically,
Lichtenberg figures (created by HV measuring equipment such as Klydonographs)
were a powerful tool for measuring the polarity and
magnitude of transient overvoltages on power lines during direct and
nearby lightning strikes. These early measurements were critical for the
development of reliable electrical power transmission and distribution
Lichtenberg figures are still used as a forensic clue for identifying
the cause of injury or death of human and animal lightning victims.
of Lichtenberg figures and charge detrapping in polymers are revealing
important details on the mechanisms that are involved in the
degradation and electrical breakdown of solid insulating materials.
There may be future medical applications as well. In 2009, a team of researchers at Texas A&M University proposed using
3D Lichtenberg figures created within various polymeric materials as
"templates" for growing blood vessels (vascular tissue).
There are significant similarities between branching Lichtenberg
figures and animal circulatory systems - a fact not lost on many
medical researchers. The hope is that, by creating branching 3D
Lichtenberg figures inside a biodegradable polymer, such as polylactic
acid (PLA), scientists can then use these as "molds" to support the development and growth of vascular tissue. Vascularization
is essential for growing functional replacement tissues and organs. It's quite possible that the 18th century technology
of Lichtenberg figures may ultimately play a critical role in organ growth and replacement
therapy during the 21st century!
Captured Lightning Sculptures - fossilized lightning bolts
is indeed an accurate description for our sculptures. Holding a
Captured Lightning sculpture is about the closest you can come to
holding a fossilized lightning bolt.
Each Lichtenberg figure is unique - a one-of-a
kind treasure, sculpted in exquisite detail by the same titanic forces contained
within natural lightning. Captured Lightning sculptures are completely
safe - they have been completely discharged and they have no trace
of radioactivity or X-rays.
Two dimensional photos cannot begin to capture the beauty and exquisite detail of our 3D
sculptures. Following are a pair of 3-D images that can be rotated 360
degrees so that you can more fully
appreciate the detail within some of our doubly-irradiated sculptures. Once the images have been completely
downloaded, you can drag your mouse over the image to rotate each for a full 360
degree view. [Note: because of the large image size, a high speed Internet connection is recommended].
3D Rotatable Image
3D Rotatable Image
(Courtesy of Theodore Gray)
(Courtesy of Theodore Gray)
few people have actually seen
or held one of these rare objects of scientific art. Far fewer have had the
opportunity to own sculptures as beautiful and spectacular as these.
Stoneridge Engineering is proud to be the world's most experienced
provider of these rare treasures.
Can I make my own Lichtenberg Figures?
Unfortunately, because electrons must be injected deep into the
acrylic, it takes a multimillion-volt electron accelerator to make 3D
Captured Lightning sculptures. However, 2D Lichtenberg figures can
be made on the surfaces of some materials, such as carbonized
Lichtenberg figures on wood, or as dust figures on the surfaces of some
plastics. Some artists have used this technique to make 2D works of art. To make carbonized figures, a high voltage (HV) power source, such
ignition coil or neon sign transformer, is required. The experiment
should be done
outside since it generates a significant amount of smoke and some small
flames. Two nails or pins are pounded into the wood with a gap of 4 - 10 inches.
wood surface is then lightly sprayed with a saltwater solution to make it
partially conductive, and the high voltage source is connected across
the two nails. When high voltage is applied, carbonized
paths begin to form near the nails. Accompanied by lots of smoke and
even small flames, they begin branching as they grow towards each other.
The heat from the process dries out the nearby surface, causing the branches to head
in various directions, sometimes even in directions away from the opposite nail. The carbonized paths eventually grow to form Lichtenberg
Figures with "roots" at each
nail. This technique must be done VERY
carefully, since it involves using dangerously high voltages and water
method to adjust the voltage (such as a variable autotransformer or
Variac) helps to control the discharge process and will improve the
shape of the
resulting figure. The following video
clip shows this technique using a 9,000 volt 30 mA neon sign
transformer as the high voltage source:
How can I get a Captured Lightning sculpture of my very own?
offer a wide selection of Captured Lightning sculptures that range in size from
affordable 2 x 2 inch specimens through museum quality two inch thick blocks as large as 15 inches by 20 inches. Please visit Gallery 1 or Gallery 2
to select a sculpture at the right price for you. We also offer
a wide variety of lighted bases with white, blue, and multi-color
color changing options. Many of these are available with UK, Australian,
or EC power options. Our light bases illuminate the
delicate patterns within, causing the discharge channels to glow so that the finest
hair-like details become visible. We also offer a variety of attractively-priced factory 2nd sculptures discounted to 50% off regular price. Be sure to visit our Eye Candy page to see some of the best artistic and experimental work by Stoneridge Engineering and some of our very creative friends.
physical experiment which makes a bang is always worth more than a
quiet one. Therefore a man cannot strongly enough ask of Heaven: if it
wants to let him discover something, may it be something that makes a
bang. It will resound into eternity.”
– Lichtenberg, Georg Christoph, and Albert Leitzmann. 1906. "Georg Christoph LichtenbergsAphorismen: nach den Handschriften.
Drittes Heft, 1775-1779," page 326. Originally in German, from Lichtenberg's Booklet F, Aphorism 1138, Oct 11-13, 1778.
(Thanks to Fermilab scientist and author, Bill Higgins for researching the source of the above quote).
"Thunder is good; thunder is impressive. But it is the lightning that does the work." - Mark Twain
References and Further Reading: 1. Gross, Bernard, "Irradiation Effects in Plexiglas", Journal of Polymer Science, Volume 27, 1958, Issue 115, Pages 135 - 143 2.
Hashishes. Yuzo, "Two Hundred Years of Lichtenberg Figures", Journal of
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3. Chadwick, K. H., "The Effect of Light Exposure on the Optical
Density of Irradiated Clear Polymethylmethacrylate", 1972 Phys. Med.
Biol. 17, Pages 88-93 4.
Chadwick, K. H., and Leenhouts, H. P., "Fading of
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Gardner, Donald G., et. al., "Radiation-induced changes in the index of
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M. Foust, General Electric Review: Instruments for Lightning
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34, #4, April, 1931, Pages 235-246
13. Watson, Alan and Dow, Julian, "Emission Processes Accompanying
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Due to a Lightning Strike", New England Journal of Medicine, Volume
343:1536, November 23, 2000, Number 21, Images in Clinical Medicine
16. H. Hiraoka, "Radiation Chemistry of Poly(methacrylates)", Radiation Chemistry, March 1977, pages 121-130
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Effects in Solid Dielectrics", Journal of Applied Physics,
September 1967, Volume 38, Issue 10, pages 3904-3907
18. Yu. S. Deev, M. S. Kruglyi, V. K. Lyapidevskii and V. I. Serenkov,
"Mechanism underlying the formation of dendritic or tree-like channels
in a dielectric irradiated with charged particles", Atomic
Energy, Volume 29, Number 4, October, 1970, pages 1037-1040
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al., Lecture Notes in Physics 567 (Springer, Berlin 2001)
Vershinin, S.V. Barakhvostov, "Electron Processes in the Pulse
Breakdown of Solid Dielectrics", 3rd International Conference on
“Technical and Physical Problems in Power Engineering”, (TPE-2006), May
29-31, 2006 - Gazi University, Ankara, Turkey (covers detonation theory of high field breakdown in solid dielectrics) 21.
Vershinin, Yu. N., "Parameters of Electronic Detonation in Solid
Dielectrics", Technical Physics, Vol. 47, No. 12, 2002, pages 1524–1528.
Translated from Zhurnal TekhnicheskoÏ Fiziki, Vol. 72, No. 12,
2002, pp. 39–43, ISSN: 10637842
22. Budenstein, P.P., "Dielectric Breakdown in Solids", Technical Report
RG-75-25, US Army Missile Command, December 20, 1974, DTIC accession
23. C. M. Cooke, E. R. Williams and K. A. Wright, "Space Charge
Stimulated Growth of Electrical Trees", Proc. Intl Conf on Properties
and Applications of Dielectric Materials, Xian, China, 1985, Pages 1-6 24. N, I, Kuskova, "Spark Discharges in Condensed Media", Technical Physics, Volume 46, Number 2, 2001, pages 182-185
25. Theodore Gray, "Theo Gray's Mad Science: Experiments You Can Do At Home - But Probably Shouldn't", Black Dog & Leventhal Publishers, 2009, ISBN 978-1579127916
26. Jen-Huang Huang, Jeongyun Kim, et al, "Rapid Fabrication of
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