N=2 ICRH of H majority plasmas in JET-ILW

Journal Article · Thu Dec 10 00:00:00 EST 2015 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4936486· OSTI ID:22496195

Van Eester, D.; Kazakov, Y.; Crombé, K. ^[1]; Jacquet, P.; Monakhov, I.; Rimini, F.; Kiptily, V.; Santala, M. ^[2]; Goniche, M.; Colas, L.; Dumont, R. ^[3]

---

1. LPP-ERM-KMS, Association EUROFUSION-Belgian State, TEC partner, Brussels (Belgium)
2. CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom)
3. IRFM, Association EUROFUSION-CEA, Saint-Paul-Lez-Durance (France)

Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = w{sub ci}) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w = 2w{sub ci}) typically requires pre-heating of the plasma ions to become efficient. Recently, w = 2w{sub ci} ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for P{sub ICRH}>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (n{sub e0}<3x10{sup 19}/m{sup 3}), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported.

• OSTI ID: 22496195
• Journal Information: AIP Conference Proceedings, Vol. 1689, Issue 1; Conference: 21. topical conference on radio frequency power in plasmas, Lake Arrowhead, CA (United States), 27-29 Apr 2015; Other Information: (c) 2015 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTIVITY
BEAM INJECTION
ELECTRIC FIELDS
H-MODE PLASMA CONFINEMENT
HYDROGEN
ICR HEATING
ION CYCLOTRON-RESONANCE
IONS
JETS
LARMOR RADIUS
L-MODE PLASMA CONFINEMENT
MAGNETIC FIELDS
MEV RANGE
PLASMA DENSITY
POLARIZATION
RADIOWAVE RADIATION
WALL EFFECTS