Design of long pulse/steady state negative hydrogen ion sources for fusion applications
By using parameters of ion sources when operating in a pulsed mode and without cooling (pulse length < 0.1 s), requirements have been determined for a long pulse (several seconds) or steady state operating mode and two sources have been designed and fabricated. First of the two is a penning source, designed for a steady state operation with a cathode power density of 1 kW/cm/sup 2/. For the range of cathode power densities between 0.2 kW/cm/sup 2/ and 1 Kw/cm/sup 2/, nucleated boiling has to be used for heat removal; below 0.2 kW/cm/sup 2/ water flow cooling suffices. Although this source should deliver 0.3 to 0.5 A of H/sup -/ ions in a steady state operation and at full power, the other source, which has a magnetron geometry, is more promising. The latter incorporates two new features compared to first designs, geometrical focusing of fast, primary negative hydrogen ions from the cathode into the extraction slit, and a wider discharge gap in the back of the source. These two changes have resulted in an improvement of the power and gas efficiencies by a factor of 3 to 4 and in a reduction of the cathode power density by an order of magnitude. The source has water cooling for all the electrodes, because maximum power densities will not be higher than 0.2 kW/cm/sup 2/. Very recently a modification of this magnetron source is being considered; it consists of plasma injection into the source from a hollow cathode discharge.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6778613
- Report Number(s):
- BNL-28561; CONF-801111-23; TRN: 81-000726
- Resource Relation:
- Conference: 6. conference on application of accelerators in research and industry, Denton, TX, USA, Nov 1980
- Country of Publication:
- United States
- Language:
- English
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