The effects of plasma deformability on the feedback stabilization of axisymmetric modes in tokamak plasmas [report]

D.J. Ward, S.C. Jardin
1992 unpublished
NOTICE This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibilityfor the accuracy, completeness, or usefulness of any information, apparatus, product,or process disclosed,or represents that its use would not infringe privately owned rights. Reference herein to any specific
more » ... to any specific commercial produce, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarilyconstituteor imply its endorsement, recommendation,or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarilystate or reflect those of the United States Government or any agency thereof. tLQ.TJ.C.E This report has been reproduceddirectly from the best available copy. . Available to DOE and DOE contractorsfrom the: Office of Scientificand Technical Information P.O. Box 62 Oak Ridge, TN 37831; Pricesavailable from (615) 57e-8401. Abstract The effects of plasma deformability on the feedbackstabilization of axisymmetric modes oftokamak plasmasarestudied, ltisseenthatplasmaswithstrongly shapedcross sections haveunstable motion different from a rigid shift. Furthermore, theplacementof i passive conductors isshown to modifythe non-rigid componentsof theeigenfunction in a way thatreducesthe stabilizing eddy currents in theseConductors. Passive feedback results usingseveral equilibria ofvaryingshapearepresented. The eigenfunction isalso modified undertheeffects ofactive feedback. Thisdeformation isseentodepend strongly on the position of the fluxloopswhich areused to determineplasma vertical position for the active feedbacksystem. The variations of thesenon-rigid components of the eigcnfunction alwaysserveto reducethestabilizing effect of theactive feedbacksystem by reducingthe measurablepoloidal fluxat the flux,loop locations. Activefeedback resuJ.ts arepresented forthe PBX-M tokamak configuration.
doi:10.2172/10115427 fatcat:jgrdadwcrrf33lgprndetqlt6e