Enhanced penetration of neutral-beam-injected ions by vertically asymmetric toroidal-field ripple
The penetration length of energetic neutral-atom beams injected into a tokamak plasma can be effectively increased by a large factor, if the beams are injected vertically and the toroidal magnetic field has significant ripple below the midplane. The energetic ions resulting from ionization of the fast neutrals are ripple-trapped and drift upward to the midplane region. The ripple must decrease substantially in the region above the midplane, so that the ions can be captured and retained in the central plasma region during their entire slowing-down period. Orbit calculations with a Monte Carlo guiding-center code demonstrate the feasibility of this trapping process. 110 to 150-keV deuterons can be deposited near the center of plasmas with (n/sub e/) a Z/sub eff/ approximately 10/sup 17/ cm/sup -2/, when the ripple near the magnetic axis and in the region below is of order 1 percent.
- Research Organization:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Organization:
- US Energy Research and Development Administration (ERDA)
- DOE Contract Number:
- E(11-1)-3073
- OSTI ID:
- 7192544
- Report Number(s):
- MATT-1206; TRN: 76-015797
- Country of Publication:
- United States
- Language:
- English
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