Enhanced surface production in H- ion sources by introducing a negatively biased secondary electrode.
Rev Sci Instrum
; 81(2): 02A702, 2010 Feb.
Article
em En
| MEDLINE
| ID: mdl-20192372
ABSTRACT
A transformer coupled plasma negative hydrogen ion source with an external rf antenna has been developed at SNU, which is capable of continuous operation with long lifetime. A positively biased plasma electrode (PE) has been successfully used for the optimization of H(-) extraction. With molybdenum-coated stainless steel PE, the enhancement of H(-) production at the electrode surface was observed at the bias voltage lower than the plasma potential. However, the low bias voltage is unfavorable to H(-) beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H(-) production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H(-) production is clearly enhanced although the SE itself reduces H(-) beam currents because of suppressed electron transport in front of the PE. In this configuration enhancement of surface productions is most pronounced in tantalum electrode among various electrode materials.
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01-internacional
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MEDLINE
Idioma:
En
Revista:
Rev Sci Instrum
Ano de publicação:
2010
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Article