1. magnetic confinement - ENEA - Fusione

46
1. MAGNETIC CONFINEMENT
1.3 Plasma Theory
present parameters, i.e., at r/a=0.2, 2
0.6
s≡rq’/q=-0.58, q=4.4, α H ≡-R 0 q 2 (dβ/dr), 1.5
0.4
∆’=0.125, α H =0.515, β H =0.0072, 1
η H =0.395, ν H /ν A =0.43, ρ LH /a=0.019.
0.5
0.2
The fast ion tail distribution function is
0
Maxwelllian in energy, with a pitch
0
angle distribution highly peaked around
-0.5
-0.2
µB 0 /E=1, µ being the magnetic moment. -1
Results for the growth rate and the -1.5 -0.4
0 0.2 0.4 0.6 0.8 1
mode frequency of the EPM are shown
r/a
in figure 1.43. It is evident that the range
of unstable mode numbers corresponds well to the experimentally observed modes.
The reason why the mode can be considered a resonantly excited EPM and not a
toroidal Alfvén eigenmode (TAE) is given by the strength of the growth rate, which
is comparable with the gap width. A more articulated explanation of this
interpretation is provided in [1.66].
Consider modes localised near
0 1 2 3 4
r 0 (for the present parameters 0.05
0.6
r 0 /a=0.49), where q has a
minimum given by q 0 .
0.04
Consider also a given toroidal
mode number n and a poloidal
0.4
mode number m such that the 0.03
normalised parallel wave
vectors Ω A,m =nq 0 -m0. It is then
0.2
readily demonstrated that the
condition under which
0.01
continuum damping is
minimised is that with 0.00
0.0
–1/2