2009
DOI: 10.1063/1.3273706
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Abstract: Abstract. The goal of the high harmonic fast wave (HHFW) research on NSTX is to maximize the coupling of RF power to the core of the plasma by minimizing the coupling of RF power to edge loss processes. HHFW core plasma heating efficiency in helium and deuterium L-mode discharges is found to improve markedly on NSTX when the density 2 cm in front of the antenna is reduced below that for the onset of perpendicular wave propagation (n onset ∝ B*k || 2 /ω). In NSTX, the observed RF power losses in the plasma edge… Show more

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Cited by 16 publications
(12 citation statements)
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“…3 Recently significant improvements in HHFW core heating efficiency were achieved by employing lithium conditioning 12 to reduce the edge density in order to move n crit farther from the antenna and first wall. 13,14 As a result core heating at lower k was considerably enhanced. Core electron heating and an increase in plasma stored energy were clearly observed for the first time during k =−3 m −1 rf heating of deuterium discharges.…”
Section: Introductionmentioning
confidence: 97%
See 1 more Smart Citation
“…3 Recently significant improvements in HHFW core heating efficiency were achieved by employing lithium conditioning 12 to reduce the edge density in order to move n crit farther from the antenna and first wall. 13,14 As a result core heating at lower k was considerably enhanced. Core electron heating and an increase in plasma stored energy were clearly observed for the first time during k =−3 m −1 rf heating of deuterium discharges.…”
Section: Introductionmentioning
confidence: 97%
“…Fast camera images prior to the growth of the ELM do not show the usual helical ELM structure. 13 Thus the ELM appears to be caused by the removal of the rf power via an arc or rf pulse turnoff.…”
Section: -3mentioning
confidence: 99%
“…Lithium coating has also contributed to improving the heating of electrons in the core plasma by HHFW RF power in NSTX [24]. After extensive lithium evaporation, 3.1 MW HHFW heating launched with a parallel wavenumber k || = ±14 m −1 (180° RF phase difference between antenna elements) produced central electron temperatures up to 5 keV in deuterium plasmas at a toroidal magnetic field of B T = 0.55 T. When the RF phase between elements was varied to change the wavelength, the heating efficiency was similar for k || = −7 m −1 and significant heating was even observed for the fastest waves with k || = −3.5 m −1 which was not the case before lithium was applied.…”
Section: Impurity Concentration (%)mentioning
confidence: 99%
“…3 Recently significant improvements in HHFW core heating efficiency were achieved by employing lithium conditioning 12 to reduce the edge density in order to move n crit farther from the antenna and first wall. 13,14 As a result core heating at lower k was considerably enhanced. Core electron heating and an increase in plasma stored energy were clearly observed for the first time during k =−3 m −1 rf heating of deuterium discharges.…”
Section: Introductionmentioning
confidence: 92%
“…Electron heating was shifted off axis and less heating was measured at k =−8 m −1 than at k = −13 m −1 , similar to the heating efficiency trend measured in L-mode plasmas. 13 About 66% of the rf power ͑ϳ1.2 MW͒ was estimated to couple to the plasma at k = −13 m −1 and about 40% ͑ϳ0.7 MW͒ was coupled at k =−8 m −1 . MPTS edge density data indicated that the edge density was below n crit for the case with k = −13 m −1 heating but it was above n crit for the case with k =−8 m −1 heating.…”
Section: -3mentioning
confidence: 99%