Electron cyclotron resonance heating and current drive in toroidal fusion plasmas

A review of experiments and theory of electron cyclotron resonance heating (ECRH) and current drive (ECCD) is presented. An outline of the basic linear theory of wave propagation and absorption in the electron cyclotron range of frequencies and their harmonics is given and compared with experimental results from many devices. The experimental data base on quasilinear and nonlinear physics as well as on parametric wave decay is reviewed and compared to theory. Experiments and theory on doppler shifted absorption either by bulk or tail electrons (which can be created by other means) are discussed. ECRH provides means for controlled plasma breakdown and current ramp up in tokamaks and plays a key role in net current-free stellarator research. Start-up was investigated in many tokamaks and stellarators and the results are discussed in the light of the present day theoretical understanding. The role of ECRH to improve the understanding of both particle and energy confinement is described and special heating correlated features, such as 'density pump out' during ECRH are discussed. The application of modulated ECRH for perturbative heat wave studies and the comparison with both sawtooth heat pulse propagation and the steady state power balance analysis is presented. Electron cyclotron current drive is a possible method for current profile and MHD control in tokamaks and provides means for bootstrap current compensation in stellarators. The basic theory of electron cyclotron current drive is presented and compared to experiments in both tokamaks and stellarators. Experiments on sawtooth stabilization and MHD control by ECRH or ECCD are discussed and compared to theory. An increasing number of fusion devices is equipped with ECRH for bulk heating and sophisticated plasma physics investigations. A remarkable extension of the accessible plasma parameter range became possible by the recent development of sources with high power (1 MW) and frequency (110-160 GHz). Particular emphasis is given to new experiments and the refinement of theory incorporating plasma phenomena and the mutual impact on the wave physics.

[1]  V. Erckmann,et al.  Electron Cyclotron Resonance Heating Experiments in the Wendelstein VII-A Stellarator , 1985 .

[2]  H. Weitzner,et al.  Absorption of waves in the second harmonic resonance layer , 1985 .

[3]  D. Brower,et al.  Core turbulence and transport studies on the Texas Experimental Tokamak , 1992 .

[4]  E. Ott,et al.  Theory of Electron Cyclotron Resonance Heating of Tokamak Plasmas. , 1979 .

[5]  Georg Kühner,et al.  Electron thermal conductivity from heat wave propagation in Wendelstein 7-AS , 1992 .

[6]  J. D. Bell,et al.  Heat pulse propagation studies in TFTR , 1986 .

[7]  Victor L. Granatstein,et al.  Heating at the Electron Cyclotron Frequency in the ISX-B Tokamak , 1980 .

[8]  Kenneth W Gentle,et al.  Dependence of heat pulse propagation on transport mechanisms: Consequences of nonconstant transport coefficients , 1988 .

[9]  Nathaniel J. Fisch,et al.  Theory of current-drive in plasmas , 1987 .

[10]  M. O'Brien,et al.  Effect of energy loss on electron cyclotron current drive in tokamaks , 1989 .

[11]  M. W. Alcock,et al.  ECRH current drive studies in the CLEO tokamak , 1988 .

[12]  E. A. Lazarus,et al.  Low voltage Ohmic and electron cyclotron heating assisted startup in DIII-D , 1991 .

[13]  David L. T. Anderson,et al.  Radiofrequency plasma breakdown in a modular stellarator , 1988 .

[14]  M. Okabayashi,et al.  Determination of the Electron Thermal Conductivity across Magnetic Surfaces in the FM-1 Spherator , 1974 .

[15]  E. Doyle,et al.  Physics of the L-mode to H-mode transition in tokamaks , 1992 .

[16]  Mark Dwain Carter,et al.  Second harmonic electron cyclotron breakdown in stellarators , 1987 .

[17]  McGuire,et al.  Peaked density profiles in circular-limiter H modes on the TFTR tokamak. , 1990, Physical review letters.

[18]  N. Fisch.  Conductivity of rf‐heated plasma , 1985 .

[19]  Petty,et al.  Inward energy transport in tokamak plasmas. , 1992, Physical review letters.

[20]  Cohen,et al.  Nonlinear absorption of intense microwave pulses. , 1987, Physical review letters.

[21]  P. Mantica,et al.  Broadband fluctuations and particle transport in the edge plasma during ECRH in DITE , 1991 .

[22]  G. Hogeweij,et al.  Tokamak transport studies using perturbation analysis , 1990 .

[23]  Wagner,et al.  Observation of a high-confinement regime in a tokamak plasma with ion cyclotron resonance heating. , 1987, Physical review letters.

[24]  J. Shohet,et al.  Radio frequency breakdown and electron confinement time in a stellarator , 1986 .

[25]  Snider,et al.  Observation of H-mode confinement in the DIII-D tokamak with electron cyclotron heating. , 1988, Physical review letters.

[26]  T N Todd.  MHD control and ECCD in Compass-D , 1993 .

[27]  I. Bernstein,et al.  Geometric optics in space− and time−varying plasmas , 1975 .

[28]  Wagner,et al.  Experimental study of the principles governing tokamak transport. , 1986, Physical review letters.

[29]  M. Fontanesi,et al.  Modelling of electron-cyclotron plasma formation and preheating in Tokamaks , 1985 .

[30]  G. L. Jahns,et al.  Internal disruptions in tokamaks , 1977 .

[31]  F. Wagner,et al.  Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak , 1982 .

[32]  H. E. Mynick,et al.  Effect of the ambipolar potential on stellarator confinement , 1983 .

[33]  Peters,et al.  Simultaneous propagation of heat waves induced by sawteeth and electron cyclotron heating power modulation in the RTP tokamak. , 1993, Physical review letters.

[34]  R. L. Haye,et al.  Electron cyclotron heating experiments on the JFT‐2 tokamak using an inside launch antenna , 1982 .

[35]  G. G. Kelley,et al.  Preionization and start‐up in the ISX‐B tokamak using electron cyclotron heating at 28 GHz , 1984 .

[36]  L. Spitzer,et al.  TRANSPORT PHENOMENA IN A COMPLETELY IONIZED GAS , 1953 .

[37]  R. Cano,et al.  Electron cyclotron emission and absorption in fusion plasmas , 1983 .

[38]  H. Weitzner,et al.  An eikonal expansion of the Vlasov–Maxwell equations valid near cyclotron resonance , 1980 .

[39]  Effects of radial transport on current drive in tokamaks , 1991 .

[40]  B. Lloyd,et al.  LOW VOLTAGE START-UP IN THE CLEO TOKAMAK USING ECRH , 1986 .

[41]  I. Fidone,et al.  Absorption of cyclotron waves at down-shifted frequencies by an energetic electron tail in the PLT tokamak , 1985 .

[42]  Y. Takeiri,et al.  Scalings of energy confinement and density limit in stellarator/heliotron devices , 1990 .

[43]  Manfred Thumm,et al.  First ECRH-experiments on the W VII-A stellarator , 1984 .

[44]  J. Rice,et al.  Transport analysis of injected impurities in currentless Heliotron E plasmas , 1987 .

[45]  R. Kirkwood,et al.  Measurement of suprathermal electrons in tokamaks via electron cyclotron transmission , 1990 .

[46]  T. L. Rhodes,et al.  The structure of magnetic fluctuations in tokamaks: Observations in the TEXT tokamak , 1991 .

[47]  F. Sardei,et al.  Confinement studies on the Wendelstein VII-AS stellarator , 1990 .

[48]  G. Giruzzi,et al.  Effective opacity of dense tokamak plasmas at the second electron cyclotron harmonic , 1982 .

[49]  Y-K.M. Peng,et al.  Electron cyclotron/upper hybrid resonant pre-ionization in the ISX-B tokamak , 1981 .

[50]  Hitoshi Tanaka,et al.  Toroidal plasma production by electron cyclotron heating in the WT-2 device , 1986 .

[51]  H. Matsumoto,et al.  Transition from the L-mode to the H-mode by electron cyclotron heating of a tokamak edge plasma , 1988 .

[52]  V. Erckmann,et al.  Electron Cyclotron Resonance Heating Transmission Line and Launching System for the Wendelstein VII-AS Stellarator , 1990 .

[53]  Cross-effect on electron cyclotron and lower hybrid current drive in tokamak plasmas , 1987 .

[54]  K. Hackett,et al.  Observation of the parametric decay instability during electron cyclotron resonance heating on the Versator II tokamak , 1982 .

[55]  Anthony B. Murphy,et al.  Initial operation of the Wendelstein 7AS advanced stellarator , 1989 .

[56]  D. Sing,et al.  LETTER: Refraction and absorption measurements of a focused ECH beam , 1993 .

[57]  M. Cox,et al.  Solution of three-dimensional Fokker-Planck equations for tokamak plasmas using an operator splitting technique , 1991 .

[58]  F. Sardei,et al.  Electron Cyclotron Resonance Heating in the Wendelstein VII-A Stellarator , 1986 .

[59]  B. P. Duval,et al.  X- and O-mode electron cyclotron heating breakdown and startup in TCA , 1992 .

[60]  R. Cohen,et al.  Theory of free-electron-laser heating and current drive in magnetized plasmas , 1991 .

[61]  R. Chang,et al.  Nonlinear wave effects in laboratory plasmas: A comparison between theory and experiment , 1978 .

[62]  Tadashi Sekiguchi,et al.  Plasma Physics and Controlled Nuclear Fusion Research , 1987 .

[63]  S. Ide,et al.  Non-inductive current drive using second harmonic electron cyclotron waves on the WT-3 tokamak , 1991 .

[64]  D. Start.  Coupling between ECRH-driven and ohmic plasma currents , 1983 .

[65]  V. Erckmann,et al.  Current drive and bootstrap current in stellarators , 1992 .

[66]  M. Porkolab,et al.  Observation of plasma heating due to parametric instabilities at the upper hybrid and at the cyclotron harmonic frequencies , 1973 .

[67]  Georg Kühner,et al.  Experimental and neoclassical electron heat transport in the LMFP regime for the stellarators W7‐A, L‐2, and W7‐AS , 1993 .

[68]  G. Giruzzi.  Impact of magnetic turbulence on rf current drive , 1992 .

[69]  Geist,et al.  H mode of the W 7-AS stellarator. , 1993, Physical review letters.

[70]  N. Ohyabu,et al.  A simple model of energy confinement in tokamaks , 1986 .

[71]  Mori,et al.  H mode observed in the JFT-2M tokamak with edge heating by electron cyclotron waves. , 1989, Physical review letters.

[72]  T. Hatori,et al.  Diffusion induced by cyclotron resonance heating , 1986 .

[73]  S. P. Hirshman,et al.  Classical collisional theory of beam‐driven plasma currents , 1980 .

[74]  V. Alikaev,et al.  Current drive by electron cyclotron waves , 1991 .

[75]  H. Weitzner,et al.  Ray Tracing near the Electron Cyclotron Frequency with Application to EBT , 1980, IEEE Transactions on Plasma Science.

[76]  V. Chan,et al.  Kinetic theory of electron cyclotron current drive in a toroidal device , 1982 .

[77]  B. Tubbing,et al.  Tokamak heat transport – a study of heat pulse propagation in JET , 1987 .

[78]  T. K. Chu,et al.  Sawtooth stabilization through island pressure enhancement , 1987 .

[79]  R. Prater,et al.  Interpretation of electron cyclotron heating results in overdense plasma in Doublet III , 1987 .

[80]  S. Ide,et al.  Enhancement of efficiency for lower hybrid current drive by electron cyclotron heating in the WT-2 tokamak , 1986 .

[81]  A. Litvak,et al.  Electron-cyclotron heating of plasma in toroidal systems , 1977 .

[82]  F. Sardei,et al.  Transport in Stellarators , 1993 .

[83]  Y. Dnestrovskij,et al.  Ion energy balance in T-10 , 1987 .

[84]  S. Migliuolo.  REVIEW PAPER: Theory of ideal and resistive m=1 modes in tokamaks , 1993 .

[85]  B. Carreras.  Transport mechanisms acting in toroidal devices: A theoretician's view , 1992 .

[86]  M. Porkolab,et al.  Experimental Investigation of Plasma Heating by a High-Frequency Electric Field near the Electron Cyclotron Resonance in the FM-1 Spherator , 1973 .

[87]  Brown,et al.  Nonlinear absorption of high power free-electron-laser-generated microwaves at electron cyclotron resonance heating frequencies in the MTX tokamak. , 1994, Physical review letters.

[88]  J. Heikkinen,et al.  Parametric scattering in electron‐cyclotron resonance heating , 1986 .

[89]  Charles F. Kennel,et al.  Velocity Space Diffusion from Weak Plasma Turbulence in a Magnetic Field , 1966 .

[90]  Fom Ecrh Team.  The electron cyclotron resonance experiment on TFR , 1988 .

[91]  O. Pogutse,et al.  The kinetic theory of runaway electron beam instability in a tokamak , 1978 .

[92]  R. Chang,et al.  Parametric instability of plasma waves in a magnetic field, due to high-frequency electric fields , 1972 .

[93]  J. Y. Chen,et al.  Suppression of m=2 islands by electron cyclotron heating in the Texas Experimental Tokamak: Experiment and theory , 1993 .

[94]  Cho,et al.  Plasma current generation and sustainment by electron cyclotron waves, in the WT-2 tokamak. , 1986, Physical review letters.

[95]  Atsushi Fukuyama,et al.  Confinement improvement in H-mode-like plasmas in helical systems , 1993 .

[96]  Allen H. Boozer,et al.  Creating an asymmetric plasma resistivity with waves , 1980 .

[97]  N. Fujisawa,et al.  A radio frequency current drive model and its comparison with experiments , 1988 .

[98]  D. R. Whaley,et al.  Electron cyclotron resonance heating on the TCA tokamak , 1993 .

[99]  James R. Wilson,et al.  Power transmission and coupling for radiofrequency heating of plasmas , 1989 .

[100]  M. O'Brien,et al.  Fokker–Planck studies of high power electron cyclotron heating in tokamaks , 1986 .

[101]  Terry Kammash,et al.  Microwave start-up of tokamak plasmas near electron cyclotron and upper hybrid resonances , 1977 .

[102]  R. Kirkwood,et al.  Measurement of the relaxation of electron parallel momentum in a tokamak , 1991 .

[103]  Kunizo Ohkubo,et al.  Pre-ionization and heating of stellarator plasma at electron cyclotron frequency in JIPP T-II , 1981 .

[104]  U. Stroth,et al.  Transport in toroidal devices-the experimentalist's view , 1992 .

[105]  Charles F. F. Karney.  Fokker-Planck and Quasilinear Codes , 1986 .

[106]  H. Matsumoto,et al.  Measurement of Peripheral Electron Temperature by Electron Cyclotron Emission during the H-Mode Transition in JFT-2M Tokamak , 1987 .

[107]  R. Prater,et al.  Electron Cyclotron Heating and Pre-Ionization in the JFT-2 Tokamak , 1985 .

[108]  Up-shifted frequency electron-cyclotron current drive in a lower hybrid current drive plasma , 1993 .

[109]  W Vii-A Team,et al.  Impurity transport in the wendelstein VII-A stellarator , 1985 .

[110]  S. Wolfe,et al.  Electron cyclotron resonant heating with an ordinary-mode antenna in the JFT-2 tokamak , 1981 .

[111]  Y. Uesugi,et al.  Second harmonic electron cyclotron heating of lower hybrid current driven plasma in JFT-2M , 1991 .

[112]  Mori,et al.  Avoidance of qa=3 disruption by electron cyclotron heating in the JFT-2M tokamak. , 1992, Physical review letters.

[113]  ASDEX-Upgrade team,et al.  The H-Mode of ASDEX , 1989 .

[114]  Osamu Motojima,et al.  Confinement of a Currentless Plasma in the Heliotron-E , 1982 .

[115]  J. Manickam,et al.  Attainment of high confinement in neutral beam heated divertor discharges in the PDX tokamak , 1984 .

[116]  C. Bishop.  Stability of localized MHD modes in divertor tokamaks – a picture of the H-mode , 1986 .

[117]  M. Taguchi.  Poloidal electric field due to electron-cyclotron resonance heating in tokamaks , 1992, Journal of Plasma Physics.

[118]  Lao,et al.  Regime of very high confinement in the boronized DIII-D tokamak. , 1991, Physical review letters.

[119]  R. Prater,et al.  Resonance localization and poloidal electric field due to cyclotron wave heating in Tokamak plasmas , 1984 .

[120]  M. Cox,et al.  Thermal wave studies of electron transport using modulated ECRH , 1993 .

[121]  G. L. Jahns,et al.  Experimental Measurement of Electron Heat Diffusivity in a Tokamak , 1977 .

[122]  M. Taguchi.  Radial diffusion equation for rf-driven current density , 1993 .

[123]  Y. Terumichi,et al.  Suppression of HF instability due to RF-driven current by applying ECH in the WT-2 tokamak , 1983 .

[124]  G. Giruzzi,et al.  Electron‐cyclotron heating of a tokamak reactor with the extraordinary mode , 1986 .

[125]  S. K. Wong,et al.  Poloidal electric field generated by electron cyclotron heating in a collisional tokamak plasma , 1987 .

[126]  R. Harvey,et al.  A trapped‐passing fluid model for tokamak neoclassical transport , 1992 .

[127]  L. Demeio,et al.  Velocity space diffusion of electrons induced by a beam of electron cyclotron waves of finite size in toroidal geometry , 1986 .

[128]  E. Mazzucato,et al.  Propagation of a Gaussian beam in a nonhomogeneous plasma , 1989 .

[129]  John Lohr,et al.  Modification of sawteeth by second harmonic electron-cyclotron heating in a tokamak , 1989 .

[130]  N. Fisch.  Confining a Tokamak Plasma with rf-Driven Currents. , 1978 .

[131]  M. M. Dremin,et al.  Electron cyclotron current drive experiments on T-10 , 1992 .

[132]  Thomas M. Antonsen,et al.  Radio frequency current generation by waves in toroidal geometry , 1982 .

[133]  M. Tokman,et al.  Quasilinear theory of cyclotron heating of plasma in toroidal systems by monochromatic radiation , 1983 .

[134]  R. Prater,et al.  Measurement of thermal transport by synchronous detection of modulated electron cyclotron heating in the Doublet III tokamak , 1986 .

[135]  E. Westerhof.  Tearing mode stabilization by local current density perturbations , 1990 .

[136]  R. L. Meyer,et al.  Electron cyclotron heating in rf current‐driven tokamak plasmas , 1984 .

[137]  S. Wolfe,et al.  Extraordinary mode absorption at the electron cyclotron harmonic frequencies as a tokamak electron temperature diagnostic , 1987 .

[138]  T. H. Stix.  Radiation and absorption via mode conversion in an in homogeneous collisionfree plasma. , 1965 .

[139]  Snider,et al.  Electron-cyclotron-current-drive experiments in the DIII-D tokamak. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[140]  G. Giruzzi,et al.  Diagnosis of superthermal electrons using cyclotron radiation , 1990 .