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Characterization of the CW starter plasma RF matching network for operating the SNS H⁻ ion source with lower H₂ flows.
- Source :
-
The Review of scientific instruments [Rev Sci Instrum] 2016 Feb; Vol. 87 (2), pp. 02B143. - Publication Year :
- 2016
-
Abstract
- The Spallation Neutron Source H(-) ion source is operated with a pulsed 2-MHz RF (50-60 kW) to produce the 1-ms long, ∼50 mA H(-) beams at 60 Hz. A continuous low power (∼300 W) 13.56-MHz RF plasma, which is initially ignited with a H2 pressure bump, serves as starter plasma for the pulsed high power 2-MHz RF discharges. To reduce the risk of plasma outages at lower H2 flow rates which is desired for improved performance of the following radio frequency quadrupole, the 13.56-MHz RF matching network was characterized over a broad range of its two tuning capacitors. The H-α line intensity of the 13.56-MHz RF plasma and the reflected power of the 13.56-MHz RF were mapped against the capacitor settings. Optimal tunes for the maximum H-α intensity are consistent with the optimal tunes for minimum reflected power. Low limits of the H2 flow rate not causing plasma outages were explored within the range of the map. A tune region that allows lower H2 flow rate has been identified, which differs from the optimal tune for global minimum reflected power that was mostly used in the past.
Details
- Language :
- English
- ISSN :
- 1089-7623
- Volume :
- 87
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- The Review of scientific instruments
- Publication Type :
- Academic Journal
- Accession number :
- 26932025
- Full Text :
- https://doi.org/10.1063/1.4937772