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A new ten-channel pulsed radar reflectometer has been taken into operation at the Torus Experiment for Technology Oriented Research-94. The system will be used simultaneously as a density profile and as a density fluctuation diagnostic. Ten density layers from 0.4×10[sup 19] to 4×10[sup 19] m[sup -3] can be probed simultaneously at 2 MHz. The design of the diagnostic has undergone some changes, to improve reliability of the system. Examples of time delay measurements are shown. These examples illustrate the fluctuation capabilities of the diagnostic at high time resolution, as well as the response of the different channels to density profile changes. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

To aid the scientific research program on the Toroidal Experiment for Technology Oriented Research (TEXTOR)-94 tokamak, the existing electron cyclotron emission (ECE) diagnostics for the electron temperature studies are being extended with new systems that feature a good temporal and radial resolution. Using the possibility of obtaining the data on a fast time scale, ECE systems allow one to study fast phenomena like the dynamics of small-scale structures such as magnetic islands and transport barriers and microscopic temperature fluctuations throughout the plasma. The quantitative information about nonthermal electron populations can be obtained from the comparison of the second and third harmonic emission. A new 16-channel frequency tunable radiometer and a four-channel second harmonic system were recently installed at TEXTOR-94. The detailed description of the new TEXTOR-94 ECE systems and the recent results will be given and discussed in this article. © 2001 American Institute of Physics. [DOI: 10.1063/1. [ABSTRACT FROM AUTHOR]

Electron cyclotron emission imaging (ECE imaging or ECEI) is a novel plasma diagnostic technique for the study of electron temperature profiles and fluctuations in magnetic fusion plasma devices. Instead of a single receiver located in the tokamak midplane as in conventional ECE radiometers, ECEI systems utilize large diameter imaging optics coupled with planar millimeter-wave imaging arrays to form multichannel ECE diagnostics with excellent spatial resolution. Combined with specially designed imaging optics, the use of these compact, low cost arrays has resulted in the excellent spatial resolution of the ECEI systems, the unique capability of two-dimensional measurements, and flexibility in the measurement of plasma fluctuations. Technical details and principles of this emerging diagnostic technique are described in this article. Illustrative experimental results are presented, together with a discussion of the further development of the diagnostic. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

After more than 4 decades of fusion research, plasma transport in tokamaks remains an outstanding issue. The standard hypothesis, that the observed anomalous transport is caused by small scale turbulence, is consistent with experimental observations, but it is neither based on a self-consistent theory of plasma turbulence nor on an exhaustive set of turbulence measurements. One of the major obstacles to the development of a satisfactory anomalous transport theory is the inability of standard fluctuation diagnostics to provide the full spectrum of turbulent fluctuations. The result is a nearly complete reliance on numerical simulations. Unfortunately, in spite of the enormous capabilities of today’s computers, this is extremely unsatisfactory since any theory or simulation of plasma turbulence can only be driven by direct experimental observations. The first step in achieving such data was the highly successful UC Davis Electron Cyclotron Emission (ECE) Imaging system, which was first developed for use on the TEXT-U tokamak and later modified for use on the Rijnhuizen Tokamak Project tokamak.1 Here, correlation techniques are applied to spatially resolved second harmonic ECE signals to provide detailed information about the microturbulence associated with T[sub e] fluctuations. The present work extends this work by developing a similar technique for spatially resolved n[sub e] fluctuations via microwave imaging reflectometry. The result is a diagnostic capable of the simultaneous measurement of both T[sub e] and n[sub e] fluctuations (both turbulent and coherent) and profiles on toroidal devices such as tokamaks and stellarators. A 16 channel ECE imaging system has recently been installed on the Torus Experiment for Technology Oriented Research (TEXTOR) tokamak. A prototype millimeter wave imaging reflectometry system will be installed on TEXTOR in July 2000, which will operate in V band (50–75 GHz) and reflect from the X-mode cutoff. Data col... [ABSTRACT FROM AUTHOR]