Optical thickness corrections to ECE measurement of electron temperature in IR-T1 tokamak (original) (raw)
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Electron cyclotron emission imaging in tokamak plasmas
Applied Optics, 2010
We discuss the recent history and latest developments of the electron cyclotron emission imaging diagnostic technique, wherein electron temperature is measured in magnetically confined plasmas with twodimensional spatial resolution. The key enabling technologies for this technique are the large-aperture optical systems and the linear detector arrays sensitive to millimeter-wavelength radiation. We present the status and recent progress on existing instruments as well as new systems under development for future experiments. We also discuss data analysis techniques relevant to plasma imaging diagnostics and present recent temperature fluctuation results from the tokamak experiment for technology oriented research (TEXTOR).
Plasma Physics and Controlled Fusion, 2002
Measurements of electron cyclotron emission (ECE) from the high field side of the TCV tokamak have been made on plasmas heated by second and third harmonic X-mode electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD). Suprathermal ECE, up to a factor of six in excess of thermal emission, is detected in the presence of second harmonic X-mode (X2) ECCD and of third harmonic X-mode (X3) ECH. The measured ECE spectra are modelled using a bi-Maxwellian describing the bulk and the suprathermal electron populations. Suprathermal temperatures between 10 and 50 keV and densities in the range 1 × 10 17 -6 × 10 18 m −3 are obtained, and correspond to 3-15 bulk temperatures and 1-20% bulk densities. Good agreement between ECE suprathermal temperatures and energetic photon temperatures, measured by a hard x-ray camera, is found. For optically thin X3 low field side injection in the presence of X2 CO-ECCD, the suprathermal population partly explains the discrepancy between global and first pass absorption measurements.
Review of Scientific Instruments, 1999
The electron cyclotron emission ͑ECE͒ diagnostic on FTU tokamak is routinely performed with a Michelson interferometer with spectral range extending up to 1300 GHz. The diagnostic allowed accurate electron temperature measurements during the recent 140 GHz electron cyclotron resonance heating ͑ECRH͒ experiments on FTU. Very accurate measurements have been performed on a wide range of electron temperatures and profile peaking. The ECE measurements have been compared with Thomson scattering and with observations of x-ray spectra from highly stripped molybdenum ions. The suprathermal emission in these conditions has been studied.
International Journal of Infrared and Millimeter Waves, 1994
The design of a multi-channel heterodyne radiometer used to determine the electron temperature in the edge region of the ASDEX Upgrade (AUG) tokamak plasma by measuring the microwave electron cyclotron emission (ECE) is described. A novel feature of the system is the use of both side-bands of a heterodyne mixer to maximise the available radiation bandwidth. First measurements of the temperature profile in the edge region during the development of the H-mode plasmas and marfes are presented and discussed.
Symmetry
It is predicted that in ITER, due to high values of electron temperature and magnetic field strength, electron cyclotron (EC) radiation emitted by plasma will be a significant source (together with external EC radiation injected for auxiliary plasma heating and non-inductive current drive) of additional thermal and electromagnetic loads for microwave and optical diagnostics. The spectral distribution of plasma EC radiation is particularly important to consider in millimeter-wave diagnostics, namely for high- and low-magnetic-field side reflectometry, plasma position reflectometry, and collective Thomson scattering diagnostic, because the transmission lines of these diagnostics yield the transport of EC waves emitted by the plasma. The development of semi-analytical methods used to describe the spectral distribution of plasma-generated EC radiation in tokamaks, starting from the work of S. Tamor, is based on the dominance of multiple reflections of this radiation from the first wall ...
Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)
Physics of Plasmas, 2003
In noninductively driven discharges, 0.9 MW second harmonic ͑X2͒ off-axis co-electron cyclotron current drive deposition is combined with 0.45 MW X2 central heating to create an electron internal transport barrier ͑eITB͒ in steady plasma conditions resulting in a 1.6-fold increase of the confinement time ( Ee ) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction ͑up to 80%͒ and is sustained for up to 10 current redistribution times. A linear dependence of the confinement improvement on the product of the global shear reversal factor (q 0 /q min ) and the reversed shear volume ( q-min 2 ) is shown. In other discharges heated with X2 the sawteeth are destabilized ͑respectively stabilized͒ when heating just inside ͑respectively outside͒ the qϭ1 surface. Control of the sawteeth may allow the avoidance of neoclassical tearing modes that can be seeded by the sawtooth instability. Results on H-mode and highly elongated plasmas using the newly completed third harmonic ͑X3͒ system and achieving up to 100% absorption are also discussed, along with comparison of experimental results with the TORAY-GA ray tracing code ͓K. Matsuda, IEEE Trans. Plasma Sci. PS-17, 6 ͑1989͒; R. H. Cohen, Phys. Fluids 30, 2442 ͑1987͔͒.
Overview of Experimental Studies on IR-T1 Tokamak
An overview of experimental studies on IR-T1 tokamak is presented. Several issues of plasma displacement measurement are investigated. An analytic solution of the Biot–Savart law, which is used to calculate magnetic fields created by toroidal plasma current, is presented. Results of calculations are compared with the experimental data obtained in no-plasma shots with a toroidal current-carrying coil positioned inside the vessel to simulate the plasma movements. The results show a good linear behavior of plasma position measurements. An array of Mirnov coils employed for measurement of plasma position, too. The results show that Mirnov array can not be used for this measurement without concerning high field side errors. An external resonant helical magnetic field (RHF) applied to plasma. The aim of these experiments was to understand the effect of RHF on light impurities radiation and horizontal displacement measurements. Measurements results of visible line emissions of O II , C III...