Two-component r.f. regime of D+He<sup>3</sup>fusion with lowered neutron yield

Longinov, A. V.; Павлов, С. С.; Степанов, К.Н.

doi:10.1088/0741-3335/34/1/007

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“…Both quantities exhibit a nearly linear dependence on the RF power applied. One indeed expects an increased absorption efficiency for increasing ion temperature T i and density N i : as was described in [25,26] the single-pass absorption coefficient P absorbed /P in = 1 − exp(−2η) for majority heating at the fundamental cyclotron frequency has a damping rate 2η which scales as 2η = ω pi /cRn 2 T i /(m i c 2 ) with ω pi the (majority) ion plasma frequency, c the speed of light, R the major radius, n the parallel refractive index and m i the ion mass. It is important to mention that a considerable enhancement of the radiated power was observed during the application of ICRF heating in these experiments, a consequence of the rather poor single-pass absorption of the scenario.…”

Section: Results Of Icrh At the Fundamental Frequency Of The Majority...mentioning

confidence: 61%

Fundamental ion cyclotron resonance heating of JET deuterium plasmas

Krasilnikov

Eester²,

Lerche³

et al. 2009

Plasma Phys. Control. Fusion

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Radio frequency heating of majority ions is of prime importance for understanding the basic role of auxiliary heating in the activated D-T phase of ITER. Majority Deuterium Ion-Cyclotron Resonance Heating (ICRH) experiments at the fundamental cyclotron frequency were performed in JET. In spite of the poor antenna coupling at the lowest possible commissioned RF frequency (25MHz), this heating scheme proved promising when adopted in combination with D Neutral Beam Injection (NBI). The experiments were performed in a ~90% D, 5% H plasma with some pulses including traces of Be and Ar. Up to 2MW of ICRH power was applied with dipole phasing in conjunction tõ 6MW of NBI power, either using 80keV "normal" beam or 130keV "tangential" beam injection. The toroidal magnetic field strength was typically B 0 = 3.3T, providing core ICRH of the bulk D ions. The effect of fundamental D ICRH was clearly demonstrated in these experiments: By adding 25% of heating power (P ICRH = 1.7MW / P NBI+OH = 7MW) the fusion power was increased up to 30-50%, depending on the type of NBI adopted. At this power level, the ion and electron temperatures increased from T i ~ 4.0keV and T e ~ 4.5keV (NBI-only phase) to T i ~ 5.5keV and T e ~ 5.2keV (ICRH+NBI phase), respectively. The increase in the neutron yield was stronger when 80keV rather than 130keV Deuterons were injected in the plasma. It is shown that the neutron rate, the diamagnetic energy and the electron as well as ion temperature scale roughly linearly with the applied RF power. A synergistic effect of the combined use of ICRF and NBI heating was observed: (i) The number of neutron counts measured by the neutron camera during the combined ICRF+NBI phases of the discharges exceeded the sum of the individual counts of the NBI-only and ICRF-only phases; (ii) A substantial increase in the number of slowing-down beam ions was detected by the TOFOR spectrometer when ICRF power was switched-on; (iii) A small D subpopulation with energies slightly above the NBI launch energy were detected by the neutral particle analyzer and gray spectroscopy.

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Section: Results Of Icrh At the Fundamental Frequency Of The Majority...mentioning

confidence: 61%