Fusion Project: Principal systems
Vacuum chamber
The vacuum chamber provides the clean, nearly empty environment necessary for the desired acceleration and collision of fuel ions. The high vacuum system was constructed almost entirely of surplus, scrounged and handmade components, mostly made of 304 stainless steel. The system currently suffers from a tiny leak which needs to be found and eliminated before operational testing can commence.
Vacuum pumps
A Sargent-Welch model 3102 belt-drive (!) turbomolecular pump, backed by a Marvac model A20 dual-stage rotary vane pump, allows the system to be evacuated to approximately 10^(-7) mmHg. The pumps together consume approximately 500W-700W in operation, and make a considerable racket. Recently-discovered seal degradation on both pumps (resulting in gradual loss of oil) may necessitate repair or replacement of one or both units.
Pressure measurement
A Bendix GT-340A thermistor vacuum gauge monitors the turbo-pump foreline pressure, while an MKS Instruments 325 Moducell (Pirani-type gauge) and a Balzers IKR 250 cold-cathode ionization gauge provide a combined pressure measurement range of approximately 100 mmHg to 10^(-8) mmHg in the chamber itself.
Deuterium injection system
A Matheson model 3320 gas regulator and an Innovus model 1100 mass flow controller will allow an electronically-controlled flow of deuterium to be injected into the chamber on demand. A closed-loop control system is in development.
High voltage power supply
A high-voltage power supply built around a 90kVp, 10mA transformer designed for a dental X-ray head provides the high voltage necessary for acceleration of the deuterium ions. The transformer and rectifier operate under dielectric oil in a sealed tank. Output is varied by means of a variable autotransformer ("Variac") and a saturable reactor (for rough manual control of input voltage and current, respectively). A closed-loop electronic control system is planned for more precise regulation of actual output voltage and current.
Control interface
In its current state, the system operates largely under direct manual control. Following initial operational tests, development of more sophisticated electronic control systems will proceed.
A hardware/software solution is being developed to provide a unified interface for monitoring and control of all systems, as well as automated data acquisition for later analysis of experiment results.
Neutron metrology
See the Neutron Detector page for more details.
A small (20 cm length) boron trifluoride neutron detector tube in a cylindrical high-density polyethylene moderator allows for detection of the 2.45MeV fast neutrons generated by D-D fusion reactions. The electronic hardware to power the tube and discriminate neutron events from gamma rays and electrical noise is in a usable state, though some work remains before meaningful measurements will be possible.
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