Sheath structure in negative ion sources for fusion (invited)

Journal Article · Wed Feb 15 00:00:00 EST 2012 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3670339· OSTI ID:22063915

McAdams, R; King, D B; Surrey, E ^[1]; Holmes, A J. T. ^[2]

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1. EURATOM/CCFE Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)
2. Marcham Scientific, Hungerford, Berkshire RG17 0LH (United Kingdom)

In fusion negative ion sources, the negative ions are formed on the caesiated plasma grid predominantly by hydrogen atoms from the plasma. The space charge of the negative ions leaving the wall is not fully compensated by incoming positive ions and at high enough emission a virtual cathode is formed. This virtual cathode limits the flux of negative ions transported across the sheath to the plasma. A 1D collisionless model of the sheath is presented taking into account the virtual cathode. The model will be applied to examples of the ion source operation. Extension of the model to the bulk plasma shows good agreement with experimental data. A possible role for fast ions is discussed.

• OSTI ID: 22063915
• Journal Information: Review of Scientific Instruments, Vol. 83, Issue 2; Conference: ICIS 2011: 14. international conference on ion sources, Giardini-Naxos, Sicily (Italy), 12-16 Sep 2011; Other Information: (c) 2012 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
43 PARTICLE ACCELERATORS
ANIONS
CATHODES
CATIONS
CHARGED-PARTICLE TRANSPORT
EXPERIMENTAL DATA
HYDROGEN
ION SOURCES
PLASMA
PLASMA SHEATH
SPACE CHARGE