Wall conditioning towards the utilization in ITER

Abstract Wall conditioning provides an effective means for reducing both impurities and recycling from the plasma surrounding surface. A wide variety of techniques have been developed during the last few decades for conditioning the plasma facing surface. With the presence of magnetic fields, electron cyclotron resonant (ECR) and ion cyclotron resonant (ICR) discharge cleaning techniques have been explored, which could be used for next generation superconducting magnetic confined devices, such as ITER. Efforts have been made on the application of ICR conditioning on many devices and significant progress has been made. A new and simple method for future wall conditioning, high frequency glow discharge cleaning (HF-GDC), has been developed. HF-GDC operates in the presence of strong magnetic field (0.5–2 T) at frequencies of 20–100 kHz stably for a wide range of gas pressures. In this paper, all these techniques are reviewed and their proper application in ITER are discussed.

[1]  J. Li,et al.  The first results of O-ICR experiments to remove re-deposited layers and hydrogen in the HT-7 superconducting tokamak , 2005 .

[2]  Jet Efda Contributors,et al.  Tritium retention in next step devices and the requirements for mitigation and removal techniques , 2006 .

[3]  Dennis G. Whyte,et al.  Tritium recovery in ITER by radiative plasma terminations , 2004 .

[4]  H. F. Dylla,et al.  Glow discharge conditioning of the PDX vacuum vessel , 1980 .

[5]  K. Kawahata,et al.  ECR discharge cleaning experiment in the JIPP T-II , 1981 .

[6]  N. Asakura,et al.  RF heated wall conditioning discharges in JT-60U , 2009 .

[7]  J. Shan,et al.  ECR discharge cleaning and followed He GDC on HT-7 tokamak , 2009 .

[8]  智 東島,et al.  JT-60Uにおける第一壁コンディショニング—不純物および水素リサイクリングの制御 , 1999 .

[9]  N. Fujisawa,et al.  Electron cyclotron resonance discharge cleaning of JFT-2 Tokamak (Jaeri) , 1980 .

[10]  G. Oost,et al.  ICRF wall conditioning at TEXTOR-94 in the presence of a 2.25 T magnetic field , 1997 .

[11]  V. Moiseenko,et al.  Analysis of ICRE (ω ⩽ ωci) plasma production in large scale tokamaks , 1992 .

[12]  M. Sakamoto,et al.  Wall conditioning using 2.45 GHz ECR-DC on superconducting tokamak TRIAM-1M , 2001 .

[13]  Eric Gauthier,et al.  ICRF/ECR plasma production for wall conditioning in TEXTOR-94 , 2002 .

[14]  G. Jackson,et al.  Particle control in DIII-D with helium glow discharge conditioning , 1990 .

[15]  Y. Sakamoto,et al.  Surface composition changes of inconel 625 during RG and ECR discharge cleaning of textor at 300°C☆ , 1984 .

[16]  Eric Gauthier,et al.  Review of radio frequency conditioning discharges with magnetic fields in superconducting fusion reactors , 2005 .

[17]  Mark Dwain Carter,et al.  Plasma production using radiofrequency fields near or below the ion cyclotron range of frequencies , 1990 .

[18]  D. Hartmann,et al.  ICRF wall conditioning experiments in the W7-AS stellarator , 2001 .

[19]  Y. Ikeda,et al.  Electron cyclotron resonance discharge cleaning by using LHRF system on JT-60U , 1999 .

[20]  C. H. Skinner,et al.  Recent Advances on Hydrogen Retention in ITER’s Plasma-Facing Materials: Beryllium, Carbon, and Tungsten , 2008 .

[21]  J. Winter,et al.  REVIEW ARTICLE: Wall conditioning in fusion devices and its influence on plasma performance , 1996 .

[22]  J. Li,et al.  Removal of re-deposited layers and release of trapped hydrogen by He/O-ICR plasma in a HT-7 superconducting tokamak , 2006 .

[23]  Joachim Roth,et al.  Tritium inventory in ITER plasma-facing materials and tritium removal procedures , 2008 .

[24]  V. Philipps,et al.  Removal of redeposited layers and hydrogen release by oxygen ventilation of TEXTOR-94 , 1999 .

[25]  G. Saibene,et al.  Review of vacuum vessel conditioning procedures at JET and their impact on plasma operation , 1995 .

[26]  P. Wienhold,et al.  Cleaning and conditioning of the walls of plasma devices by glow discharges in hydrogen , 1984 .

[27]  C. H. Skinner,et al.  Plasma{material interactions in current tokamaks and their implications for next step fusion reactors , 2001 .

[28]  Jiarong Luo,et al.  ICRF boronization - A new technique towards high efficiency wall coating for superconducting tokamak reactors , 1999 .

[29]  S. Rosanvallon,et al.  In-situ tokamak laser applications for detritiation and co-deposited layers studies , 2007 .

[30]  K. Gibson,et al.  Efficacy of photon cleaning of JET divertor tiles , 2007 .

[31]  V. Philipps,et al.  Removal of carbon layers by oxygen glow discharges in TEXTOR , 2007 .

[32]  S. Itoh,et al.  ECR-discharge cleaning for TRIAM-1M , 1997 .

[33]  B. Leikind,et al.  Improvement of wall conditioning of the tandem mirror GAMMA 10 by ECR discharge cleaning , 1989 .

[34]  N. Ashikawa,et al.  Deposits removal and hydrogen release on co-deposited films exposed to O-ICR and O-GDC plasmas in HT-7 , 2007 .

[35]  R. Taylor,et al.  Trapping and removal of oxygen in tokamaks , 1977 .

[36]  Jian-gang Li,et al.  ECR plasmas for wall conditioning of the HT-7 tokamak , 2008 .

[37]  W. Wampler,et al.  Electron cyclotron discharge cleaning (ECDC) experiments on Alcator C-Mod , 1998 .

[38]  K. Kawahata,et al.  Wall Conditioning at the Starting Phase of LHD , 1999 .

[39]  Shuichi Takamura,et al.  Chapter 4: Power and particle control , 2007 .

[40]  M. Nishi,et al.  Application of glow discharges for tritium removal from JT-60U vacuum vessel , 2004 .