Aachen PK 2003 – wissenschaftliches Programm
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P: Plasmaphysik
P 10: Poster II
P 10.8: Poster
Dienstag, 18. März 2003, 17:30–19:15, Foyer
Electron heating associated with small-scale fluctuations excited in helicon plasma — •Bernd Clarenbach1, Michael Krämer1, Bernd Lorenz1, and Valeriy Selenin2 — 1Experimentalphysik II, Ruhr-Universität Bochum, D-44780 — 2Ioffe Physico-Technical Institute, St. Petersburg, Russia
The frequency spectra of the fluctuations in the helicon discharge HE-L (ne ≤ 2· 1019m−3,PHF≤ 2 kW, f0 =13.56 MHz, Te≈ 3 eV,B<0.2 T, p≤ 1 Pa Argon or p≤ 3 Pa Helium, rp=74 mm, Lp=1100 mm) measured by various RF probe diagnostics and Enhanced microwave back-scattering near the Upper Hybrid resonance (ES) reveal broad side-bands at f0. The correspondingly broad spectra in the low frequency range can be attributed to small-scale ion-sound fluctuations (wave dispersion measured by cross-correlation ES) excited by the helicon wave field. The turbulent fluctuations lead to anomalously strong damping compared to collisional damping. To examine the local energy transfer to the electrons associated with the turbulent fluctuations, temporally and spatially resolved measurements of the emission line intensities, plasma density, helicon wave field and fluctuations were simultaneously performed in a wide range of plasma parameters. The comparison of the neutral and ion line emission yields information on the electron heating in different rages of the EEDF. It turns out that the heating is closely connected with the evolution of the turbulence originating from a parametric instability.
Supported by the DFG (KR 1058 & SFB 1944, Teilprojekt A7)