skip to main content

SciTech ConnectSciTech Connect

Title: Performance and data analysis aspects of the new DIII-D monostatic profile reflectometer system

A new frequency-modulated profile reflectometer system, featuring a monostatic antenna geometry (using one microwave antenna for both launch and receive), has been installed on the DIII-D tokamak, providing a first experimental test of this measurement approach for profile reflectometry. Significant features of the new system are briefly described in this paper, including the new monostatic arrangement, use of overmoded, broadband transmission waveguide, and dual-polarization combination/demultiplexing. Updated data processing and analysis, and in-service performance aspects of the new monostatic profile reflectometer system are also presented. By using a raytracing code (GENRAY) to determine the approximate trajectory of the probe beam, the electron density (n{sub e}) profile can be successfully reconstructed with L-mode plasmas vertically shifted by more than 10 cm off the vessel midplane. Specifically, it is demonstrated that the new system has a capability to measure n{sub e} profiles with plasma vertical offsets of up to ±17 cm. Examples are also presented of accurate, high time and spatial resolution density profile measurements made over a wide range of DIII-D conditions, e.g., the measured temporal evolution of the density profile across a L-H transition.
Authors:
; ; ; ; ; ; ;  [1]
  1. Physics and Astronomy Department, University of California, Los Angeles, California 90095 (United States)
Publication Date:
OSTI Identifier:
22308627
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANTENNAS; BEAMS; DATA ANALYSIS; DATA PROCESSING; DOUBLET-3 DEVICE; ELECTRON DENSITY; FREQUENCY MODULATION; MICROWAVE RADIATION; PERFORMANCE; PLASMA; POLARIZATION; REFLECTION; SPATIAL RESOLUTION; WAVEGUIDES