[Table of Contents]

Plasma and Fusion Research

Volume 6, 2402030 (2011)

Regular Articles

A Quasi-Coherent Electrostatic Mode in ECRH Plasmas on TJ-II
Alexander V. MELNIKOV, Leonid G. ELISEEV, Maria A. OCHANDO1), Kenichi NAGAOKA2), Enrique ASCASIBAR1), Alvaro CAPPA1), Francisco CASTEJON1), Teresa ESTRADA1), Carlos HIDALGO1), Sergey E. LYSENKO, Jose L. de PABLOS1), Maria A. PEDROSA1), Satoshi YAMAMOTO3), Shinsuke OHSHIMA3), HIBP group1,4) and TJ-II team1)
Institute of Tokamak Physics, NRC “Kurchatov Institute”, 123182, Moscow, Russia
1)
Laboratorio Nacional de Fusión por Confinamiento Magnético Asociación EURATOM-CIEMAT, 28040, Madrid, Spain
2)
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
3)
Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan
4)
Institute of Plasma Physics, NSC KIPT, 310108, Kharkov, Ukraine
(Received 6 December 2010 / Accepted 16 March 2011 / Published 27 July 2011)

Abstract

A new type of instability mode, related to suprathermal electrons, was found in extremely low-density plasmas, (ne = (0.2-0.5) × 1019 m−3) with electron cyclotron resonance heating and current drive (ECRH/ECCD) in the TJ-II heliac. The quasi-monochromatic density and plasma potential oscillations in the frequency range 20-120 kHz tend to have several “branches” with constant frequency shift between them. The typical amplitude of the mode induced potential oscillations was estimated to be ΔφEM ∼ 20 V. The mode branches have an individual and finite radial extent, odd low poloidal structure (m ≤ 5) and angular phase velocity of poloidal rotation of about 8 × 104 rad/s in the ion diamagnetic drift direction. The contribution of the mode to the turbulent particle flux ΓE×B for the observed wave vectors kθ < 3 cm−1 was found to be small in comparison with the contribution from broadband turbulence.

Keywords

electrostatic eigenmode, suprathermal electron, ECRH, TJ-II.

DOI: 10.1585/pfr.6.2402030

Full Text

PDF format (2.4Mbytes) PDF Download

References

  • [1] W. W. Heidbrink et al., Phys. Plasmas 15, 055501 (2008).
  • [2] S. E. Sharapov et al., Phys. Rev. Lett. 93, 165001 (2004).
  • [3] K. Toi et al., Nucl. Fusion 40, 1349 (2000).
  • [4] T. Ido et al., Rev. Sci. Instrum. 79, 10F318 (2008).
  • [5] A. Weller et al., Phys. Plasmas 8, 931 (2001).
  • [6] A. V. Melnikov et al., Nucl. Fusion 50, 084023 (2010).
  • [7] A.V. Melnikov et al., Plasma and Fusion Research 5, S2019 (2010).
  • [8] M. Valovic et al., Nucl. Fusion 40, 1569 (2000).
  • [9] C. B. Deng et al., Phys. Rev. Lett. 103, 025003 (2009).
  • [10] M. Isobe et al., Nucl. Fusion 50, 084007 (2010).
  • [11] K. L. Wong et al., Phys. Rev. Lett. 85, 996 (2000).
  • [12] M. A. Ochando and F. Medina, Plasma Phys. Control. Fusion 45, 221 (2003).
  • [13] L. Rodríguez-Rodrigo et al., Proc. 26th EPS Conf. Contr. Fusion and Plasma Phys. (1999) ECA, 23J, p. 353.
  • [14] I. Bondarenko et al., Rev. Sci. Instrum. 72, 583 (2001).
  • [15] A. V. Melnikov et al., Fusion Sci. Technol. 51, 31 (2007).
  • [16] M. A. Ochando et al., Fusion Sci. Technol. 50, 313 (2006).
  • [17] Yu. N. Dnestrovskij and A. V. Melnikov, Sov. J. Plasma Phys. 12, 393 (1986).
  • [18] P. C. Liewer, Nucl. Fusion 25, 543 (1985).
  • [19] F. Medina et al., 31st EPS Conf. on Plasma Physics (London, 2004) ECA, 28G, P-4.182.
  • [20] L. G. Eliseev et al., 23th IAEA Fusion Energy Conf. (Daejon, Korea, 2010), EXW/P7-17.
  • [21] E. J. Powers, Nucl. Fusion 14, 749 (1974).
  • [22] A. Melnikov et al., 37th EPS Conf. on Plasma Physics, (Dublin, 2010) P1-066.
  • [23] L. I. Krupnik et al., 33rd EPS Conf. on Plasma Physics, (Rome, 2006) ECA, 30I, P-1.138.
  • [24] L. I. Krupnik et al., AIP Conf. Proc. 875, 95 (2006).
  • [25] B. Ph. van Milligen et al., Nucl. Fusion 51, 013005 (2011).
  • [26] A. V. Melnikov et al., Plasma Phys. Control. Fusion 48, S87 (2006).
  • [27] A. Fujisawa et al., Nucl. Fusion 47, S718 (2007).
  • [28] F. Medina et al., Rev. Sci. Instrum. 2, 471 (2001).

This paper may be cited as follows:

Alexander V. MELNIKOV, Leonid G. ELISEEV, Maria A. OCHANDO, Kenichi NAGAOKA, Enrique ASCASIBAR, Alvaro CAPPA, Francisco CASTEJON, Teresa ESTRADA, Carlos HIDALGO, Sergey E. LYSENKO, Jose L. de PABLOS, Maria A. PEDROSA, Satoshi YAMAMOTO, Shinsuke OHSHIMA, HIBP group and TJ-II team, Plasma Fusion Res. 6, 2402030 (2011).