A DEMONSTRATION OF KEN SHOULDERS'
'CHARGE CLUSTER' PHENOMENA

Date: Wed, 6 Dec 2000 11:15:57 -0700
From: Hal Fox <halfox a uswest,net>
To:
Subject: Something for School

Dear William Beaty,

Ken Shoulders, in one of his papers, describes the following. It is a very instructive experiment and may lead some students to become one of the early charge-cluster engineers.

Use standard aluminum foil. Coat it with a mixture of finest silicon carbide powder (used as a grinding powder for polishing) mixed with enough epoxy to make it stick.

There is nothing exotic about mixing the epoxy and silicon carbide granules. We used black friction tape applied to the aluminum foil and then squeegee the paste onto the layer between the two tapes. You can try different thicknesses. We determined that about 0.006 inches was about optimum.

Connect a high voltage d.c. connection to the foil and the other to a needle. You will need to have a high-voltage source, such as from a TV power supply (from any old TV). Try the aluminum for both positive and negative connections. Slowly bring the needle closer to the aluminum (black coating toward the needle).

According to textbooks, it requires about 10,000 volts per centimeter to establish a spark or an arc. Have students determine at what distance and at what voltage arcs or sparks appear in this experiment.

You will note that you can create a visible (especially in the dark) flow of ions (probably caused by electrons bombarding air molecules) between the needle and the aluminum before the spark zaps. In addition, you will find the following:

1. Sparks are produced at much lower voltages than the textbooks predict.

2. The spark will entirely vaporize the silicon carbide (which has a very high vaporization temperature). Have students look up the melting and vaporization temperatures.

3. There will be a hole in the aluminum.

4. You may observe (when aluminum is anode) that the spark goes past the aluminum and turns around and goes back to the aluminum electrode.

Why does this arrangement produce sparks/arcs at lower voltages. I suggest that it is because most of the voltage drop is across the non-conducting silicon carbide layer. This is a method of creating a charge cluster.

ABOUT MEASURING

Ken works much with single shots. He charges a small capacitor to a given high voltage (maybe several hundred volts). It is easy to measure the voltage on the capacitor before a "shot" and after the shot and compute the energy used. Similarly, the output is captured in a capacitor. It is easy to compute the power output supplied to the capacitor. Shoulders has shown that it is relatively easy to get ten times as much electrical energy out as input electrical energy. The trick is to provide an input pulse that is very short to make the charge cluster and to make the output pulse as wide as possible. This is not simple because one needs to produce clusters using nanosecond, high-voltage pulses.

Have Fun!

REFERENCE

• Charge Clusters In Action K. Shoulders, S. Shoulders, 1999 (.pdf)

I first noticed this when using a VandeGraaff machine to 'zap' an aquarium bulb held in my hand. At first the glass flashed green. But then during further discharges, plasma glows were seen inside the bulb. But they grew smaller, disappeared, and were replaced by normal sparks. The VDG had somehow drilled a microscopic hole right through the glass, letting in the air and producing a visible glow. The location of the hole was adjacent to a sharp filament-support, as if the sharp grounded wire had been launching some sort of "disintegrator ray" which drilled an incredibly tiny hole through the glass. WEEEEEIRD