A virtual Simons' Hour Talk: Particle Resonances in Toroidal Plasmas

Given by: Roscoe White
Princeton Plasma Physics Lab

Note the time: 8:00am EDT / 12:00 UTC.  Zoom link will be sent via email.

Abstract: High energy particle resonances are important concerning the existence of a dense fusion capable particle distribution. They can modify the distribution and even induce particle loss.

The existence of resonances is examined for tokamaks and stellarators. For tokamaks an analytic expression is found for p, the number of poloidal elliptic points of a resonance and the energy dependence of the resonance is derived. Resonances in DIII-D, ITER, and JT60-U are examined.

For stellarators typically all resonances are present with toroidal transits l and poloidal transits p such that the ratio l/p corresponds to a value of the helicity q existing within the discharge. The mode frequency is almost entirely determined by the value of l, scaling as 1/l.

In LHD shot 65140 negative frequency resonances abound, the strongest having toroidal mode number n = 1, agreeing with analysis of the instability.

An analytic model for the distribution of resonances gives a reasonable first approximation to the resonances existing in the equilibrium.