Enhanced surface production in H{sup -} ion sources by introducing a negatively biased secondary electrode

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3273059· OSTI ID:22053820

An, Young Hwa; Jung, Bong Ki; Hwang, Y S ^[1]

---

1. Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

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{sup -} extraction. With molybdenum-coated stainless steel PE, the enhancement of H{sup -} 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{sup -} beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H{sup -} production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H{sup -} production is clearly enhanced although the SE itself reduces H{sup -} 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.

• OSTI ID: 22053820
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 2 Vol. 81; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANTENNAS
BEAM CURRENTS
BEAM EXTRACTION
CHARGE-COUPLED DEVICES
ELECTRODES
ELECTRON TRANSFER
HYDROGEN IONS 1 MINUS
ION SOURCES
MOLYBDENUM
OPTIMIZATION
PLASMA
PLASMA POTENTIAL
STAINLESS STEELS
SURFACES
TANTALUM