Design Frontiers – Science Fair Project

Science Fair Project (Van De Graaff Generator)

Van De Graaf generator discharging (30 second exposure)

The first assignment for Design Frontiers in Biology and Materiality was to recreate a favorite childhood science fair project as a personal statement. Thinking long and hard… there was 4th grade: “Robert Oppenheimer: A History of the Atomic Bomb”, 5th Grade: Ozone depletion, but the favorite had to be 6th Grade: “Van De Graaff generator” -some old school tech but still a lot of fun.

As a personal statement I hope that this revived endeavor from my childhood underscores my devotion as an artist and designer in understanding nature through applied knowledge and technology. I feel that this project illustrates how mundane everyday materials can be transformed through informed practice to generate truly beautiful phenomena.

It was a bit much for a one week assignment, but I soon realized I couldn’t NOT do this because the generator I built back in junior high never really worked as well as it should have and it has always bothered me. Standing at nearly 5 feet (just taller than me at the time) and with a sphere of about 18 inches the output should have been at least a 1,000,000 volts, but was closer to 20,000. Why?? -the wrong materials. The internet was a novelty at the time and offered little to no resources for a 6th grader looking to make a lot of static electricity… how times have changed… (if this assignment taught me one thing it’s that through retrospection and practice the internet is even more amazing than I had previously thought.)

A Van De Graaff generator works on the same principal as rubbing a balloon on your head to generate a static charge… it simply automates the process. The apparatus is pretty simple: a motor driving a belt between two rollers and collector combs… The belt carries positively charged particles from the grounded base up to the isolated collection sphere where they are eventually discharged. This repetitive cycle can generate extremely high voltages.

The variables:

• Roller Materials
• Belt Material
• Motor speed
• Collector sphere size and surface
• Distance between base and sphere
• position of combs

The materials of the rollers need to be as far from each other on the TriboElectric series as possible (similar to PH, each material has a place on a spectrum of positive or negative charge). I chose to use a PVC (-100) roller for the bottom and Polyurethane Foam (+60) for the top roller and some mystery synthetic fabric as the belt that seemed to carry a charge really well though latex or vinyl might work better (will experiment later).

Lower brush and roller assembly

I found an old kitchen mixer at the junk shop for the motor. This was a great choice… for only $5… I got a variable speed AC gear-head motor which is perfect for both making whipped cream and handling the torque while driving a tensioned belt. The “low” “med” “high” is a great feature when testing the generator.

For the sphere, the ideal is a perfectly spherical smooth surface (any sharp edges or points will cause it to discharge into the air -which mine does)… not having the time or budget for a perfect orb, I opted for two $3 mixing bowls from the dollar store joined with a band of vinyl electrical tape. As you can see below the charge is so strong that it is discharging straight through 3 layers of vinyl tape.

corona discharge

Thinking portability I chose a smaller form factor (about 32 inches tall with a 9 inch “sphere”). Standard 3 inch PVC pipe for the insulating tube and some aluminum angle stock for the base chasis.

Initial Startup
The first time I powered on the assembled rig I started it on the “low” setting and immediately felt the static charge from a few feet away and started smelling ozone caused by coronal discharge… but failed to see any big sparks… -only a few 3 to 4 inch sparks while holding my hand near the sphere.

Turning off the lights while running the generator revealed something very different though. The first notable evidence of the field being generated was the flickering pulse of the overhead fluorescent lights that were turned off -this was caused by the static charge below them (note that my studio ceilings are around 14 feet high so this was pretty impressive for such a small generator). Next I held my hand near the sphere and saw a beautiful blueish pink corona flaring out toward my hand that was not visible with the overhead lights on.

I started noticing all kinds of bizarre phenomena around the room; small sparks dancing along the metro shelving near the generator and small digital watch displays flickering and flashing white.

I decided to attempt a photo.. knowing that the the camera and its static sensitive internals and CF card were probably within dangerous range of the field… I stupidly did it anyway… evidenced here: the dissipative casing on my camera works!

I will hopefully be able to use the generator for another project… or if anyone needs a strong desktop ion source… I am for hire.