Operation of a dc large aperture volume‐production H− source
| Autor: | O. A. Anderson, J.W. Kwan, Ka-Ngo Leung, C. F. Chan, A. F. Lietzke, W. F. Steele, W. S. Cooper, G. D. Ackerman, G. J. deVries |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | Review of Scientific Instruments. 61:369-371 |
| ISSN: | 1089-7623 0034-6748 |
| DOI: | 10.1063/1.1141296 |
| Popis: | In testing a multicusp volume‐production H− ion source (20 cm diameter, 23 cm long), we optimized the gas pressure, the plasma electrode bias potential, and the magnetic filter. At the optimum pressure of 9 mTorr, the H− beam output increased linearly with discharge power. The maximum H− beam, measured with a current transformer downstream of the accelerator, was 100 mA while using a 6.67‐cm2 aperture. Presently we are limited by overheating of the cathodes by the plasma ions. Under similar discharge conditions the maximum H− current density was found to vary as a−0.7, where a is the aperture radius. Results from emittance measurements showed that the effective H− ion temperature increased with a for a>0.8 cm. Thus, the brightness of the beam decreased with increasing aperture radius. Operating the source with cesium would increase the H− output; however, our accelerator must be improved to avoid breakdowns caused by the cesium contamination. |
| Databáze: | OpenAIRE |
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