Current density measurements in Tokamak devices

Tokamak plasmas are, at present, the most studied objects in controlled thermonuclear fusion research. The basic concept of these devices relies on externally induced currents which serve the twofold purpose of heating the plasma and creating an appropriate magnetic field structure for confinement. A detailed knowledge of the current density distributions and the dependencies on the operational conditions are important for both the theoretical understanding and the practical improvement of Tokamaks. The experimental techniques for measuring the current density profile or the associated magnetic fields within the plasma are reviewed. After a brief description of the equilibrium magnetic field configuration in toroidal geometry and a short account of indirect and passive diagnostic methods, an assessment is made of the currently available techniques with respect to the state of development and the obtained results.

[1]  P. Carolan,et al.  Proposal to measure the q profile on JET by Thomson scattering , 1990 .

[2]  J. Sheffield.  A method for measuring the direction of the magnetic field in a Tokamak plasma by laser light scattering , 1972 .

[3]  S. Suckewer,et al.  Magnetic field measurements in tokamak plasmas , 1984 .

[4]  M. Martone,et al.  Thomson scattering measurements from a current carrying plasma and the determination of local current density in a Tokamak (T.T.F.2) , 1977 .

[5]  B. Pégourié,et al.  Diagnostic of the current density profile in the vicinity of q = 1: The Hα emission of ablated pellets , 1990 .

[6]  Robert S. Granetz,et al.  Soft-X-ray tomography on Alcator C , 1985 .

[7]  R. Lüst,et al.  Axialsymmetrische magnetohydrodynamische Gleichgewichtskonfigurationen , 1957 .

[8]  Wagner,et al.  Temporal behavior of the plasma current distribution in the ASDEX tokamak during lower-hybrid current drive. , 1987, Physical review letters.

[9]  R. Durst,et al.  q‐profile measurement in tokamaks using fueling pellets , 1988 .

[10]  N. R. Sauthoff,et al.  A study of disruptive instabilities in the PLT tokamak using X-ray techniques , 1978 .

[11]  L. Lao,et al.  Reconstruction of current profile parameters and plasma shapes in tokamaks , 1985 .

[12]  H. Kugel,et al.  Neutral Probe Beam q-profile measurements in PDX and PBX-M , 1988 .

[13]  P. Carolan.  Laser light scattering as a method for measuring the magnetic field direction in a plasma , 1977 .

[14]  Décoste,et al.  High resolution soft-x-ray tomography of sawtooth oscillations on the Tokamak de Varennes. , 1989, Physical review letters.

[15]  E. D. Fredrickson,et al.  Measurement of internal magnetic field pitch using Li pellet injection on TFTR (invited) , 1990 .

[16]  R. Goldston.  Radially resolved measurements of ’’q’’ on the adiabatic toroidal compressor tokamak , 1978 .

[17]  R. N. Dexter,et al.  q measurements during sawtooth oscillations in a low q tokamak , 1989 .

[18]  M. Fukao,et al.  Response of a tokamak plasma to toroidal electric field pulse and determination of the plasma current profile , 1991 .

[19]  Huang,et al.  Determination of the poloidal magnetic field profiles in a tokamak by polarization spectroscopy of an impurity ion line. , 1988, Physical review letters.

[20]  Recent Alfven-Wave Heating Results on the Tca Tokamak , 1984 .

[21]  A. Brizard,et al.  Feasibility study of using the TFTR Thomson scattering system for q profile measurements , 1986 .

[22]  G. Magyar,et al.  JET polari-interferometer , 1989 .

[23]  W. P. West.  Plasma density and poloidal field measurements on TEXT using an injected lithium beam (invited) , 1986 .

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

[25]  C. J. Barth.  Determination of the local current density by means of tangential Thomson scattering: Experimental setup, feasibility test, and preliminary observations , 1989 .

[26]  Course,et al.  Basic and advanced diagnostic techniques for fusion plasmas : proceedings of the course and workshop held in Varenna, Italy : September 3-13, 1986 , 1987 .

[27]  Gill,et al.  Rapid collapse of a plasma sawtooth oscillation in the JET tokamak. , 1986, Physical review letters.

[28]  R. Hickok,et al.  A direct measurement of plasma space potential , 1970 .

[29]  D. Meyerhofer,et al.  Measurement of current penetration during PDX discharge startup , 1985 .

[30]  H. Weisen,et al.  Observations of motional Stark features in the Balmer spectrum of deuterium in the JET plasma , 1989 .

[31]  S. Segre,et al.  The polarization of an e.m. wave propagating in a plasma with magnetic shear. The measurement of poloidal magnetic field in a Tokamak , 1972 .

[32]  L. K. Huang,et al.  Scanning polarimeter for measurement of the poloidal magnetic field in a tokamak , 1988 .

[33]  L. Lao,et al.  Determination of the safety factor in sawtoothing discharges in DIII‐D , 1991 .

[34]  A. T. Ramsey,et al.  Parallel electric resistivity in the TFTR tokamak , 1990 .

[35]  J. Lister,et al.  Determination of central q and effective mass on textor based on discrete Alfvén wave (DAW) spectrum measurements , 1990 .

[36]  H. Soltwisch.  Measurement of current-density changes during sawtooth activity in a tokamak by far-infrared polarimetry (invited) , 1988 .

[37]  R. J. Hawryluk,et al.  Neoclassical conductivity of a tokamak plasma , 1977 .

[38]  R. Granetz,et al.  X-ray tomography on JET , 1988 .

[39]  N. R. Sauthoff,et al.  Studies of internal disruptions and m=1 oscillations in tokamak discharges with soft--X-ray techniques , 1974 .

[40]  I. Fidone,et al.  Nonlinear Wave Mixing at Hybrid Frequencies in an Inhomogeneous Plasma , 1971 .

[41]  A. W. Edwards,et al.  Determination of the shear on the q = 1 surface of the JET tokamak , 1989 .

[42]  Knight,et al.  Measurements of the tokamak-safety-factor profile by means of driven resonant Alfvén waves. , 1989, Physical review letters.

[43]  J. Y. Chen,et al.  Safety factor on the axis of a tokamak during Ohmically heated sawtoothing discharges from a localized measurement of circular polarization of the Li I 6708 A line , 1990 .

[44]  P. Carolan,et al.  Measurement of magnetic fields in a tokamak using laser light scattering , 1978, Nature.

[45]  West,et al.  Measurement of the rotational transform at the axis of a tokamak. , 1987, Physical review letters.

[46]  J. O'Rourke.  The change in the safety factor profile at a sawtooth collapse , 1991 .

[47]  Roberts,et al.  Magnetic field pitch-angle measurments in the PBX-M tokamak using the motional Stark effect. , 1989, Physical review letters.

[48]  I. Fidone,et al.  Poloidal field measurements in the ST tokamak by harmonic generation at the upper hybrid layer , 1975 .