Antisymmetric RMF Current Drive in FRCs.

Uploaded on:
Category: General / Misc
Antisymmetric RMF Current Drive in FRCs R.D. Milroy, H.Y. Guo, A.L. Hoffman, and L.C. Steinhauer Redmond Plasma Material science Research center, College of Washington Theoretical
Slide 1

Antisymmetric RMF Current Drive in FRCs R.D. Milroy, H.Y. Guo, A.L. Hoffman, and L.C. Steinhauer Redmond Plasma Physics Laboratory, University of Washington Abstract Rotating Magnetic Fields (RMF) can be utilized to both frame and support Field Reversed Configurations (FRC). The expansion of even a little straightforward transverse attractive field to a FRC tends to open the field lines, prompting a worry that constrainment could be traded off. Counts demonstrate that both electron and particle circles are kept because of the cyclic way of the field line opening, yet quick electron warm conduction remains a worry unless the edge thickness can be kept up to a great degree low. It was indicated 1 that if an antisymmetric RMF is connected, the field lines stay shut for little proportions of vacuum RMF B  to outside pivotal attractive field B e . Late examinations show enhanced constrainment when antisymmetric RMF is connected, and an investigation of these outcomes 2 demonstrates that field lines stay shut for much bigger proportions of B /B e because of certainty that the RMF just in part infiltrates the FRC. With these empowering results, antisymmetric RMF will soon be tried further on the new TCS update test. We extend the investigation to incorporate a representation of the antisymmetric RMF that all the more precisely records for the reception apparatus geometry, ponder the outcomes\' affectability to exact symmetry, and focus the limit for the opening of field lines. 1 S. A. Cohen and R. D. Milroy, Phys. Plasmas, 7 , 2539, (2000) 2 H. Y. Guo, A. L. Hoffman, and L. C. Steinhauer, Phys. Plasmas 12 , 062507 (2005) But, symmetric transverse RMF still tends to open field lines Field lines just somewhat enter the FRC Antisymmetric RMF was proposed as a method for accomplishing field-line conclusion Calculations by Cohen & Milroy demonstrated that for full entrance, B /B e must be < 5% to accomplish field-line conclusion utilizing hostile to symmetric RMF. For RMF driven FRCs in TCS, B /B e > 25%, which would be too high.  However, i t has been exhibited in TCS that, because of shallow RMF entrance , it is conceivable to keep up the field lines shut, even with generally solid RMF extents.

Slide 2

Overall execution is enhanced with antisymmetric RMF Temperatures are for the most part higher at lower densities on the grounds that impacts of radiation are littler. However, there is a consistency in the higher temperatures accomplished with antisymmetric RMF. No increment in consumed RMF power. Hostile to/operation results in same normal thickness, yet higher fields are come to because of apparently higher accomplished temperature. Vitality repression is enhanced Antisymmetric  higher attractive fields Energy restriction time: ï\' cc = E FRC/P net In relentless state: P net = P rmf – P rad – P cx – P i = P cond + P conv RMF infiltration stays comparative so the RMF torque, T RMF  B  2 *, is unaltered. Yet, higher fields and more prominent fluxes are created with anit/RMF : 0.5 mWb –/RMF : 0.77 mWb – hostile to/RMF. Field-Line following with mostly entered RMF Basic FRC structure : 2D Grad-Shafranov harmony (Steinhauer). RMF outspread structure : in light of a logical model for mostly entered RMF (Hoffman). RMF pivotal structure : indicated with either an even equality (/RMF) or an odd equality ( hostile to/RMF ). Ordinary (symmetric) RMF: Field lines are open, striking end divider, with an association length: L con ~ 2.5 L FRC . Antisymmetric RMF : Field lines are kept shut even at edge, r = 0.9 r s .

Slide 3

Contours of field line length versus beginning position Contours of max. outspread degree versus beginning position Field-Line following with another model another model uses a numerically created harmony and RMF that completely infiltrates close to the closures. A n=1 B r/B z part added to incorporate the impacts of current return at midplane and reception apparatus closes. A full mapping of where field lines are open has been ascertained. Impact of hub asymmetry If the RMF is not symmetric as for the FRC, field lines are opened once more. Consider a case with the RMF moved pivotally by r s/3 concerning the FRC. Field lines are long – yet they do open. Forms of field line length versus beginning position Contours of max. spiral degree versus beginning position Imposed n=1 RMF Symmetric fields Antisymmetric fields Calculate field line length as capacity of beginning position in the x-y plane. All field lines begin at z=0. Internal “ chestnut ” area contains shut field lines. On the off chance that separatrix is near divider, field lines beginning close to the hub of symmetry will strike the divider. Standard Calculation: B ω/B z0 = 0.25, Î\' */r s = 0.15 ( relating to test ) When the same investigation is connected to ordinary symmetric RMF, the greater part of the field lines are opened. Shapes of field line length versus beginning position Contours of max. spiral degree versus beginning position Summary It has been shown tentatively, that vitality imprisonment is drastically enhanced when FRCs are framed and supported with antisymmetric RMF. Counts demonstrate that, with halfway infiltration, field lines can be shut when antisymmetric RMF is utilized. Fractional entrance permits field lines to stay shut for much higher adequacy RMF than already anticipated for full infiltration (Cohen and Milroy). An antiparallel radio wire design will be utilized on the new TCS update office, which will permit higher temperatures to be accomplished. 3D projection of field lines (length = 50 r s ), with a) began along the x and