1. 9/20/04NSTX RESULTS REVIEW 20041 NSTX rtEFIT implementation progress results NSTX 2004 RESULTS REVIEW September 20&21, 2004 REAL-TIME EQUILIBRIUM RECONSTRUCTION AND ISOFLUX CONTROL OF PLASMA SHAPE AND POSITION IN NSTX

2. 9/20/04NSTX RESULTS REVIEW 20042 rtEFIT IMPLEMENTATON NEW ALGORITHM FOR REAL TIME SHAPE CONTROL COMMISSIONED IN 2002 62 MAGNETIC FIELD AND FLUX MEASUREMENTS, 11 POLOIDAL FIELD COIL CURRENT MEASURMENTS, AND 9 LOOP VOLTAGE MEASUREMENTS FACTOR OF 4 REDUCTION IN CONTROL SYSTEM LATENCY ACHIEVED IMPROVED VERTICAL POSITION CONTROL

3. 9/20/04NSTX RESULTS REVIEW 20043 NSTX rtEFIT PROGRESS CONTROL SYSTEM HARDWARE AND SOFTWARE MODIFIED AND TESTED PRIOR TO START OF RUN PERIOD DOUBLE NULL SHOTS DEVELOPED FOR XP USE PLASMA CONTROL SYSTEM ALSO MODIFIED FOR USE OF RWM COILS (using PF4 supply) AND NON-INDUCTIVE STARTUP USING PF4 Note: RWM coils will get SPA supply upgrade in the near future

4. 9/20/04NSTX RESULTS REVIEW 20044 NSTX rtEFIT PROGRESS, cont. SHAPE CONTROL EVALUATED THROUGHOUT THE RUN PERIOD SEVERAL PROBLEMS IDENTIFIED AND CORRECTED: – Continuous hand-off between old control system and rtEFIT –Improved vertical position control with rtEFIT (made the same as old system) APPROXIMATELY 40% OF 2004 SHOTS USED rtEFIT PLANS FOR NEXT RUN PERIOD INCLUDE DEVELOPMENT OF SINGLE NULL SHOT SCENARIOS

5. 9/20/04NSTX RESULTS REVIEW 20045 Shape control 3 stage shape control development plan now complete –coil current control (1999) –Ip and position control - preprogrammed shape control (2000 - 2002) –rtEFIT/isoflux shape control (2003 - 2004) rtEFIT/isoflux control now functional and has been used successfully

6. 9/20/04NSTX RESULTS REVIEW 20046 Elongation (  ) control High l i (~1.5)double-null RF heated plasma k was increased by increasing the requested height of the X- points after 0.2 s from shot-to- shot The sudden drops in kappa do not represent a large shape change, but rather are due to algorithm in EFIT used to get kappa

7. 9/20/04NSTX RESULTS REVIEW 20047 Control of drsep (the separation at the outboard midplane between the flux surfaces on which the X-points lie) Control of drsep is achieved by adjusting the control point for PF3L (for positive drsep) to be further inside the plasma than for drsep = 0 and by using a symmetry term to control the fluxes at the two control locations at the outer midplane The X-point references are unchanged, but the actual location of the lower X-point moves.

8. 9/20/04NSTX RESULTS REVIEW 20048

9. 9/20/04NSTX RESULTS REVIEW 20049 Reproducible boundary control demonstrated over a sequence of shots Reproducible boundary to ~ 1 cm Control maintained for ~.3 sec plasma flattop Boundary Control Results

10. 9/20/04NSTX RESULTS REVIEW 200410

11. 9/20/04NSTX RESULTS REVIEW 200411 rtEFIT successfully employed on XPs: –MAST similarity XP –Edge rotation during H-modes – EBW emission XP – HHFW + NBI XPs – HHFW heating and CD XPs rtEFIT used approximately 40% of XP shots this run period Significant experience gained in using rtEFIT features Improved kappa vs. li stability regime Improved boundary and outer gap control NOTE: Development of single null shot scenarios planned for future XPs NSTX rtEFIT RESULTS SUMMARY