Finite Larmor radii effects in fast ion measurements with neutron emission spectrometry
2013 (English)In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 55, no 1, 015008- p.Article in journal (Refereed) Published
When analysing data from fast ion measurements it is normally assumed that the gyro-phase distribution of the ions is isotropic within the field of view of the measuring instrument. This assumption is not valid if the Larmor radii of the fast ions are comparable toâ€”or larger thanâ€”the gradient scale length in the spatial distribution of the ions, and if this scale length is comparable toâ€”or smaller thanâ€”the width of the field of view of the measuring instrument. In this paper the effect of such an anisotropy is demonstrated by analysing neutron emission spectrometry data from a JET experiment with deuterium neutral beams together with radiofrequency heating at the third harmonic of the deuterium cyclotron frequency. In the experiment, the neutron time-of-flight spectrometer TOFOR was used to measure the neutrons from the d(d,n) 3 He-reaction. Comparison of the experimental data with Monte Carlo calculations shows that the finite Larmor radii of the fast ions need to be included in the modelling to get a good description of the data. Similar effects are likely to be important for other fast ion diagnostics, such as Î³ -ray spectroscopy and neutral particle analysis, as well.
Place, publisher, year, edition, pages
2013. Vol. 55, no 1, 015008- p.
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:uu:diva-192528DOI: 10.1088/0741-3335/55/1/015008ISI: 000312586000028OAI: oai:DiVA.org:uu-192528DiVA: diva2:599843
18th International Stellarator Hellotron Workshop and 10th Asia Pacific Plasma Theory Conference; Australian Natl Univ, Canberra, AUSTRALIA; 30 Jan-3 Feb 2012