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approvedtridimensional_thermonuclear_instability.pdf2016-02-09 14:44:59Bruno Coppi


Author: Alessandro Cardinali
Requested Type: Poster
Submitted: 2016-02-09 14:44:47

Co-authors: B. Coppi

Contact Info:
77 Massachusetts Ave.
Cambridge, MA   02139

Abstract Text:
Tridimensional modes involving an increase of the electron temperature can be excited as a result of $alpha $-particle heating in subignited D-T fusion burning plasmas when a nearly time- independent external source of heating is applied. The analyzed modes [1] are shown to emerge from an axisymmetric toroidal configurations and are radially localized around rational magnetic surfaces corresponding to $qleft( r={{r}_{0}} right)={{{m}^{0}}}/{{{n}^{0}}}$ where ${{m}^{0}}$ and ${{n}^{0}}$ are the relevant poloidal and toroidal mode numbers. The radial width of the mode is of the order of the thermal scale distances ${{delta }_{T}}={{left( {D_{bot e}^{th}}/{D_{parallel e}^{th}} right)}^{{1}_{4}}{{left( {{{R}_{0}}}/{{{n}^{0}}}right)}^{^{1}_{2}}left( {dln q}/{dr} right)_{0}^{-1}_{2}}$. The mode has a severe damping rate, that has to be overcome by the relevant heating rate, and is ${{left( {D_{bot e}^{th}}/{D_{parallel e}^{th}}right)}^{1}_{2}}}left( {{{n}^{0}}}/{{{R}_{0}}}right){{left( {dln q}/{dr} right)}_{0}}$. Thus the temperature range to be considered is that where the D-T plasma reactivity undergoes a relatively large increase as a function of temperature. *Sponsored in part by the US DOE.
[1] B. Coppi, et al. Nucl. Fus., 55, 053011 (2015).

Plasma Production and Heating