Experimental Plans for MHD Stability in WHAM

The high density, beam-heated, high electron temperature operation of WHAM is predicated on MHD stability in an axisymmetric mirror. One path to MHD stability is using biased end rings to generate sheared flow. This poster presents the electro-mechanical development of programmable power supplies, radially segmented end rings, and limiters for biased manipulation of the radial electric field. Using the 2D anisotropic equilibrium computed from Pleiades and FBIS fast ions [1], we compute the MHD stability integrals to predict requirements for pressure-weighted stability for the good curvature region [2]. We also present numerical simulations of various E(r) profiles. We present requirements and preliminary design for the use of active feedback: an electrostatic line-tying system using a poloidally-segmented electron emitter, and magnetic feedback using saddle coils [3].

[1] D. Endrizzi et al., Journal of Plasma Physics (Accepted, 2023).

[2] D. Ryutov et al., Physics of Plasmas, 18, 092301 (2011).

[3] I. Be'ery and O. Seemann, Plasma Physics and Controlled Fusion, 57, 085005 (2015).