How to shoot electrical sparks

Jun 27, 2023

Ted Kinsman

Alex Baker is a portrait and lifestyle driven photographer based in Valencia, Spain. She works on a range of projects from commercial to fine art and has had work featured in publications such as The Daily Mail, Conde Nast Traveller and El Mundo, and has exhibited work across Europe

How to shoot electrical sparks

Jun 27, 2023

Ted Kinsman

Alex Baker is a portrait and lifestyle driven photographer based in Valencia, Spain. She works on a range of projects from commercial to fine art and has had work featured in publications such as The Daily Mail, Conde Nast Traveller and El Mundo, and has exhibited work across Europe

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How to Record Electrical Discharges with a Digital Camera

I first became interested in trying my hand at recording sparks when I noticed some intriguing static discharges recorded on old X-ray films. I knew that these patterns were sometimes captured on film as a result of static electricity, but I had no idea that they had such a rich history and played a significant role in the understanding of electricity. By 2008, I had conducted some promising experiments with X-ray film.

The recording of the patterns made by static electricity date back to the invention of the technique in 1777 by Georg Lichtenberg. Since he was the first to observe the patterns, they are referred to as Lichtenberg figures.

On a side note, Lichtenberg is also credited with designing the standard paper size (DIN A4) and outlined the benefits of a height-to-width ratio of the square root of 2. Lichtenberg recorded his original patterns in tree sap resin; modern techniques use film or digital recording techniques.

In the fall of 2018, while attending a conference in Holland, I had the opportunity to visit the Teyler Museum. During a tour, I learned about the museum’s significant contribution to the study of electrical spark patterns, thanks to the installation of a giant electrostatic machine in December 1784.

An electric spark created when a sheet of photographic film is placed between two high voltage electrodes. Initially, the film builds up a charge on the surface and acts like as a capacitor. At a certain potential voltage, the film which is a dielectric material, breaks down and allows electrons to flow. The flowing electrons superheat the air resulting in an electrical spark which is recorded in the film emulsion. Here an odd shaped electrode was placed under the sheet film. These are often called Lichtenberg Figures after the German physicist Georg Christoph Lichtenberg, who originally discovered and studied them in 1777.

I was in awe of the immense electrostatic generator, towering over two meters in height. In one corner of the room, I noticed original copper etchings showcasing Lichtenberg patterns created by the giant electrostatic machine’s molten pitch. I made a mental note to revisit my project of recording electrical patterns using both film and a digital camera.

Lichtenberg figures are created within billionths of a second (nanoseconds) when air or a plastic undergoes a dielectric breakdown that allows high voltage to pass through a material. This process is desired to make an air-gap high-speed photographic flash work. The understanding of this process allows ultra-fast air-gap flashes to operate. These types of flashes are used for high-speed applications like capturing a bullet in flight.

The creation of a Lichtenberg figure happens when a high-voltage pulse is in contact with a material. Most often, the material in contact with the high-voltage pulse is an insulator under room conditions. If the distance between the high voltage and the ground is short enough, the electricity will ionize the air and turn the air into a conductive plasma. The conductive plasma will allow electricity to travel. As the electricity travels in the air, the air continues to heat up.

Too much electricity and the air will get so hot it will expand faster than the speed of sound and make a loud noise. This is the process by which lightning creates thunder but on a larger scale. The images here are records of the heated air (plasma) giving off light. The light can come from air alone or from an air-material surface.

The surface effects of different materials yield different shaped Lichtenberg figures of different colors. The figures are dependent on the conduction, material capacitance, the strength of the electric field, and several other factors:

In conventional electrical circuits, charge moves from the positive to the negative potentials of a circuit. This notation is left over from the days before the discovery of the electron. We now know that the electron is the mobile charge and is responsible for the flow of energy. In reality, the high voltage positive spark creates a drain for the electrons in the film.

The electrons flow together as fast as they can. It turns out that the flow of electrons and the resulting corona discharge is incredibly fast and will make a Lichtenberg pattern in hundreds of nanoseconds.

Positives Spark discharges do look different from negative spark discharges. We now know that the film material is a source of electrons for a positive charge (that is, the electrons in the film will move to the positive electrode). The negative spark is a source of electrons that will flow out across the surface of the film.

A fresh sheet of film placed in a grounded experiment will yield the characteristic patterns every time. The results of experiments are not clear when a residual unknown charge has built up on the film. The results are often a mix of positive and negative discharges.

I find these experiments yield particularly beautiful and surprising results. The majority of the time, I photograph positive discharges since I like the looks of them better.

The Van de Graaff Generator

This device was invented in 1929 by physicist Robert J.  Van de Graaff at Princeton University. The construction of the device is relatively simple, as a plastic belt moves around two pulleys of different materials.  A positive charge is carried from the bottom and deposited on the top sphere. The area of the sphere is important since the top sphere acts as a charge storage device or a capacitor.

Fig 2. The simple setup for recording the spark with a digital camera.

In this setup, a second sphere is placed near the Van de Graaff sphere and acts as a spark gap for the experiment. The second sphere supplies the positive charge to the film. This setup gives very consistent and repeatable results, and a Van de Graaff generator is relatively safe for experiments as long as the design is not modified by increasing the size of the sphere or attaching external capacitors.

Fig 3. Side view of spark discharge and camera.

The base of the Van de Graaff generator acts as a ground, and the conductive base under the film is connected to this point as the reference ground for the experiment.

As the generator is run, the distance between the spheres (A and B) is adjusted to trigger a spark at the desired voltage. The distance S for the spark is the distance that is adjusted. A 30,000-volt spark will jump 1 centimeter. The sphere A of the Van de Graaff holds the charge and acts like a capacitor.

The larger the surface area of the sphere, the more charge and the higher the current of the triggered spark. It is a good idea not to modify any supplied equipment due to safety issues. The spark will travel along wire C and discharge on the emulsion side of the film. The film is placed on top of a conductive aluminium this test setup shows the spark traveling on a thick sheet of Mylar placed on top of a grounded aluminium sheet.

Fig 4: The spark supplied the illumination for the image. Note the room dust has accumulated on the plastic plate. Dust contamination is a constant source of problems when working with these techniques. Here the wire is relatively thick and coated with a heavy insulator. In an actual photo shoot, the thick wire is replaced by uninsulated thin wire for the last few centimeters.

To simplify the use of a digital camera, I use a thin bent discharge wire and photograph the discharge directly. If the test material is a non-conductor (like film), the layer of glass can be left out. I have found that sheets of mica create some unique patterns, as does different types and thickness of glass.

The thinner the con-conductive layer of glass, the stronger the electric field created and the better the electrical discharge pattern.

A thin wire is placed on the test material and is used for the spark discharge. The camera is placed directly over the subject or to the side. This technique works well for opaque materials as long as there is no possibility for the spark to travel below the surface. If fluorescent paper is used in this application, the spark can travel below the paper and not be seen by the camera.

Of course, this technique is open to a lot of experimentation. Since the high-voltage spark gives off a lot of UV light, fluorescent paper can be used to capture this light and increase the amount of light the camera can record. Transparent electrodes can be made from salt water, and numerous other configurations can be invented. Last of all – do not forget the sparks can be recorded in film.

Discharge on mica sheet placed above red fluorescent paper. A little segment of the wire can be seen in the center of the image.
Positive spark discharge on a sheet of mica, above a yellow fluorescent sheet of paper.
A negative discharge onto glass above an aluminum ground sheet.
Discharge on a sheet of glossy inkjet paper.
The discharge from an aluminum pipe on a sheet of film.

Here is a short video I made about the process of photographing sparks:

YouTube video

For more information, have a look at my recent book outlining this experiment and numerous others.

About the Author

ed Kinsman is an associate professor in the Photographic Sciences Department at Rochester Institute of Technology in Rochester, New York, where he teaches high-speed photography and scanning electron microscopy. He holds degrees in optics, physics, and science education. You can find out more about him and follow his work on his website.

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