Results from helical axis stellarators

Abstract

Helical axis stellarators produce magnetic surfaces of high rotational transform and moderate shear solely by means of external currents, with the promise of high β. Several machines with quite different toroidal, helical, and “bumpy” Fourier components of magnetic field are now producing results, including high quality magnetic surfaces, confinement mode transitions, configuration studies, and confinement consistent with International Stellarator Scaling (ISS95) scaling up to Te∼2 keV. These devices permit concept evaluation over an unprecedented configuration space, and allow basic comparisons with those designed by established and alternative optimization strategies.

A data mining algorithm for automated characterisation of fluctuations in multichannel timeseries

“…The motivation for the present work arose from the analysis of fluctuations in magnetically confined plasma during parameter scans in the H-1 flexible heliac [1,2]. The H-1 heliac is a three field-period helical axis stellarator [3] with major radius R = 1 m, minor radius r = 0.2 m and a finely tunable magnetic geometry.…”

Studies of MHD Stability Using Data Mining Technique in Helical Plasmas

“…Moreover, the entry of information about MHD instability classifications into a database enables us to exactly and quickly investigate the characteristics of MHD stability through parameter studies. The data mining technique used here has been shown to be effective for the analysis of MHD stability in H-1 [4] flexible heliac plasmas [5][6][7] for the first time. We recently applied the data mining technique to the Heliotron J [8] whose magnetic configurations have magnetic well and low magnetic shear in whole plasma.…”