<abstract xmlns="http://www.w3.org/1999/xhtml"><p> 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. </p></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.

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

Institute of Plasma Physics ASCR, v.v.i., Department of Surface and Plasma Science, Charles University in Prague, Za Slovankou 3, 18200, Praha 8, Czechia

Nukleonika

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

{"article-title":"Energy composition of high-energy neutral beams on the COMPASS tokamak"}

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...

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

Article Category: Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Published Online: Oct 26, 2016

Page range: 419 - 423

Received: Sep 26, 2015

Accepted: Feb 29, 2016

DOI: https://doi.org/10.1515/nuka-2016-0069

Keywords
tokamak, neutral beam injection (NBI), Doppler effect, beam composition, beamlet divergence

© by Klara Mitosinkova

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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

Article Category: Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Published Online: Oct 26, 2016

Page range: 419 - 423

Received: Sep 26, 2015

Accepted: Feb 29, 2016

DOI: https://doi.org/10.1515/nuka-2016-0069

Keywordstokamak, neutral beam injection (NBI), Doppler effect, beam composition, beamlet divergence

© by Klara Mitosinkova

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
tokamak, neutral beam injection (NBI), Doppler effect, beam composition, beamlet divergence