View in EDS

Regions of kinetic geodesic acoustic modes and streamers in JIPPT-IIU tokamak plasmas.

Saved in:

Bibliographic Details
Title:	Regions of kinetic geodesic acoustic modes and streamers in JIPPT-IIU tokamak plasmas.
Authors:	Hamada, Y.¹, Watari, T.², Nishizawa, A.², Yamagishi, O.², Narihara, K.², Kawasumi, Y.², Ido, T.², Kojima, M.², Toi, K.²
Source:	Nuclear Fusion. Jun2012, Vol. 52 Issue 6, p1-11. 11p.
Subjects:	Tokamaks, Plasma gases, Ion bombardment, Oscillations, Spectrum analysis, Heat radiation & absorption
Abstract:	The radial extent of kinetic geodesic acoustic modes (KGAMs) and streamers is measured using a heavy ion beam probe. Intense KGAM oscillations are observed in the core region of a low-density ohmic (OH) plasma where Te >>Ti and outside this region, streamers characterized by steepening fronts are observed. The radial profile of plasma density stays flat in the region of the streamers, showing a rise in the plasma density in two regions, one at the scrape-off layer and the other in the core region during the radial scan of sample volumes. Intense (up to eΦ/kte ∼0.1) and broad GAM oscillations (δf/f ∼0.5) are observed in the r < ap /2 region of tokamak plasmas. GAMoscillations and streamers are strongly reduced in the heated phase. In addition, the radial profile of the spectra of GAM in the heated phase is very different from that of a low-density OH plasma. The streamers and the two-step rise in the density radial profile disappear in the heated phase. [ABSTRACT FROM AUTHOR]
	Copyright of Nuclear Fusion is the property of IOP Publishing and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	The radial extent of kinetic geodesic acoustic modes (KGAMs) and streamers is measured using a heavy ion beam probe. Intense KGAM oscillations are observed in the core region of a low-density ohmic (OH) plasma where Te >>Ti and outside this region, streamers characterized by steepening fronts are observed. The radial profile of plasma density stays flat in the region of the streamers, showing a rise in the plasma density in two regions, one at the scrape-off layer and the other in the core region during the radial scan of sample volumes. Intense (up to eΦ/kte ∼0.1) and broad GAM oscillations (δf/f ∼0.5) are observed in the r < ap /2 region of tokamak plasmas. GAMoscillations and streamers are strongly reduced in the heated phase. In addition, the radial profile of the spectra of GAM in the heated phase is very different from that of a low-density OH plasma. The streamers and the two-step rise in the density radial profile disappear in the heated phase. [ABSTRACT FROM AUTHOR]
ISSN:	00295515
DOI:	10.1088/0029-5515/52/6/063023