1. bookVolume 61 (2016): Issue 4 (December 2016)
Journal Details
License
Format
Journal
eISSN
1508-5791
First Published
25 Mar 2014
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4 times per year
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English
Open Access

Energy composition of high-energy neutral beams on the COMPASS tokamak

Published Online: 26 Oct 2016
Volume & Issue: Volume 61 (2016) - Issue 4 (December 2016)
Page range: 419 - 423
Received: 26 Sep 2015
Accepted: 29 Feb 2016
Journal Details
License
Format
Journal
eISSN
1508-5791
First Published
25 Mar 2014
Publication timeframe
4 times per year
Languages
English
Abstract

The COMPASS tokamak is equipped with two identical neutral beam injectors (NBI) for additional plasma heating. They provide a beam of deuterium atoms with a power of up to ~(2 × 300) kW. We show that the neutral beam is not monoenergetic but contains several energy components. An accurate knowledge of the neutral beam power in each individual energy component is essential for a detailed description of the beam- -plasma interaction and better understanding of the NBI heating processes in the COMPASS tokamak. This paper describes the determination of individual energy components in the neutral beam from intensities of the Doppler-shifted Dα lines, which are measured by a high-resolution spectrometer viewing the neutral beam-line at the exit of NBI. Furthermore, the divergence of beamlets escaping single aperture of the last accelerating grid is deduced from the width of the Doppler-shifted lines. Recently, one of the NBI systems was modified by the removal of the Faraday copper shield from the ion source. The comparison of the beam composition and the beamlet divergence before and after this modification is also presented.

Keywords

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