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Title: TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report

Abstract

Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI/sub 2/ would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI/sub 2/ detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI/sub 2/ detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig.

Authors:
Publication Date:
Research Org.:
North Carolina State Univ., Raleigh (USA)
OSTI Identifier:
6906452
Report Number(s):
DOE/ER/53195-T1
ON: DE88015779
DOE Contract Number:
FG05-85ER53195
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 47 OTHER INSTRUMENTATION; SEMICONDUCTOR DETECTORS; FABRICATION; TFTR TOKAMAK; PLASMA DIAGNOSTICS; ALPHA PARTICLES; ALPHA SPECTROSCOPY; CHARGED PARTICLE DETECTION; CRYSTAL GROWTH; FIRST WALL; MERCURY IODIDES; OPERATION; PROGRESS REPORT; TESTING; CHARGED PARTICLES; DETECTION; DOCUMENT TYPES; HALIDES; HALOGEN COMPOUNDS; IODIDES; IODINE COMPOUNDS; MEASURING INSTRUMENTS; MERCURY COMPOUNDS; MERCURY HALIDES; RADIATION DETECTION; RADIATION DETECTORS; SPECTROSCOPY; THERMONUCLEAR REACTOR WALLS; THERMONUCLEAR REACTORS; TOKAMAK TYPE REACTORS 700102* -- Fusion Energy-- Plasma Research-- Diagnostics; 440300 -- Miscellaneous Instruments-- (-1989)

Citation Formats

Wehring, B.W.. TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report. United States: N. p., 1988. Web.
Wehring, B.W.. TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report. United States.
Wehring, B.W.. 1988. "TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report". United States. doi:.
@article{osti_6906452,
title = {TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report},
author = {Wehring, B.W.},
abstractNote = {Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI/sub 2/ would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI/sub 2/ detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI/sub 2/ detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1988,
month = 2
}

Technical Report:
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  • A method to extract energetic alphas from the edge of a tokamak plasma has been conceived and analyzed, and experiments to test the methods are being fabricated. The analysis addressed the region of alpha phase space sampled, the survivability of the foils required to implement the method, and the overall efficiency of the method. The experimental apparatus being fabricated include a detector head for a proof-of-concept test on PLT and a calibration-test stand as a support experiment for the PLT test and to support possible subsequent experiments on TFTR. A fast pulse height analysis data acquisition system was fabricated andmore » tested and is ready for use in the experiments discussed above.« less
  • This paper discusses research performed between January 1984 and July 1987; it concerned the following areas relevant to alpha particle diagnostics: charge neutralization of alphas by foils, charged fusion product test facility, and modeling the atomic interactions between the alphas and the ablation cloud of a refueling pellet. 9 refs.
  • The emphasis of the effort has been to fully explore the charge conversion (or neutralization) foil technique so that it can be used with confidence to extract and measure the alpha flux at the edge of TFTR. Two aspects of the technique are being explored. The first is a proof-of-concept experiment which has been designed and fabricated for implementation on PLT; the second are radiation and heat flux simulations of the expected environment of TFTR to estimate their effect on the technique.
  • A passive approach to the extraction and measurement of alpha particles from tokamak fusion reactors is analyzed; the construction and preliminary results of a fast data-acquisition system are described. The passive approach is the convertor foil concept whereby alphas leaving the plasma on large banana orbits strike carbon foils which slow down to around 0.5 MeV. At this energy a sizeable fraction of the alphas are neutral and hence can be analyzed by methods similar to those used in charge-exchange neutral detectors. Alpha loss orbits in TFTR, the thermal and particle flux to the foil on the TFTR edge, andmore » the limitations in detector location caused by radiation are analyzed. The fast data-acquisition system operates in the pulse-height-analysis (PHA) mode to discriminate against low-energy background radiation. It consists of an alpha detector, a commercial preamplifier, a fast PHA module (built-in house) and an inexpensive microcomputer.« less