Automatic Control of an Inertial Electrostatic Confinement Device
Condie, Micah K.
The Houghton University Farnsworth-Hirsch fusor is an inertial electrostatic confinement device designed for the purpose of studying plasmas, D-D fusion, and as a source of x-rays and neutrons for other experiments. It operates via two concentrically arranged wire spheres with a voltage difference between them of up to 30 kV, ionizing a low-pressure gas to form and confine a plasma. The voltage across the two spheres is measured using a voltage divider circuit allowing an Arduino at the bottom of the chain to measure a lower proportional voltage. The current from the HV grid to the power supply flows through an LED, floating at high voltage, the light from which is then measured at the end of a fiber-optic cable using a phototransistor circuit. The previous fusor remote operating system used LabVIEW and Digi TS4 Port servers to communicate with the high voltage power supply, pressure gauge, and mass-flow controller via ethernet, RS-232, and RS-485. It was redesigned using a python code running on a remote computer to communicate with the instrumentation directly over USB and RS-485. Furthermore, the python code implemented a PID controller so that the pressure in the chamber could be adjusted automatically, maintaining the plasma while raising the voltage. The fusor was tested using air as the ionized gas with limited success using the PID controller. Future experiments will correct the automatic system and test the system with hydrogen then deuterium.
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