This design is now out of date and it has been replaced elsewhere but the concept is the same
The power from this demonstration reactor may be demonstrated by a single turn winding around the coil supplying electrical power to light a small low voltage filament lamp.
Here is an updated design that makes the coil assembly a Tesla coil. This design protects the interrupter from high voltage. The stipulation that the wire of the main coil be brought out to a few turns at each end of the tube remains.
The new design resonates at about 6.5 KHz so the mechanical oscillator won’t work. We will need an electronic audio oscillator and power amplifier.
The RMS current in the primary is 2 amps and the drive dc potential is 12 volts so a simple 2N3055 transistor will do. The power is about 24 watt. The output of the secondary will be 12 x 1000 = 12000 volt and the current 2 ma. The plasma current will be 20 amps.
The spark gap should be about 5 mm to prevent the apparatus overheating if the fusion reaction starts.
The hydrogen is ionised by the 12,000 volt high voltage alternating potential across the gas tube.
The gas heats up first and then an avalanche breakdown occurs then the current in the main coil induces the 20 amps current in the plasma the two currents repel each other so the plasma is compressed and contained as well as heated. Pulses of fusion take place near the mid point of the coil and the pulses of thermal expansion of the ionised gas with current flowing induces more mutual current and generates electricity.
Here I have changed the buzzer for a transistor oscillator.
You may need a rheostat to regulate the primary current. This goes in series with the battery.
The bias resistor is 120 ohm, 2 watt.