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XP511. LRDIAG Model with new PF1A. Merging Start-up. PF2. Y. Takase, Y. Ono, O. Mitarai, D. Gates, J. Menard, R. Raman, J.R. Wilson, M. Yamada, S. Zweben, et al. PF3. PF1A. PF4. Demonstrate I p start-up by merging of two ST plasmas, using only outboard PF coils. PF5.
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XP511 LRDIAG Model with new PF1A Merging Start-up PF2 Y. Takase, Y. Ono, O. Mitarai, D. Gates, J. Menard, R. Raman, J.R. Wilson, M. Yamada, S. Zweben, et al. PF3 PF1A PF4 Demonstrate Ip start-up by merging of two ST plasmas, using only outboard PF coils PF5 Plasma Region • Plasmas are initiated at X-points at top/bottom of vacuum vessel (PF1A, PF2, PF4) • Ip ramped up by induction from PF coils (PF2, PF3, PF4, PF5) Rapid formation of high-b ST plasma may be realized by ion heating due to reconnection
ST Merging (TS-3): High power heating of merging enables quick formation of a high-b ST plasma
Smal l ST Coils ST High-b ST ECH ST Coils Smal l ST New Merging ST Experiment (@ Univ. Tokyo) Merging of two STs produced by external PF coils high-b ST
Example of LRDIAG Simulation PF2 Bt = 0.45 T (REC = 0.6 m) PF1A PF1A PF4 X-points PF2 PF3 PF2 PF3 PF4 PF5 PF5
Experimental Run Plan • Pressure scan (5 shots) • Toroidal field scan: Bt = 0.45 T 0.3 T, 0.6T (2 shots) • Vary X-point location: RX = 0.9 m 0.75 m, 0.6 m (2 shots) • Vary PF current ramp time: 20 ms 10ms, 50ms (2 shots) [Vl = 3 V 4V, 1.7V] • Reduce EC power (4 shots) • Optimize further Ip ramp-up (~ 10 shots) [PF current ramp rate, ramp timing, relative magnitudes] • Optimize ion heating due to reconnection (~ 5 shots) ~ 100 kA of plasma current is expected, if successful
Required Capabilities • EC preionization at full power • PF4 (opposite polarity to PF5) ~ 2 kA polarities as follows (+ in the direction of Ip): PF1A +/- PF2 +/- PF3 +/- PF4 + PF5 - • HHFW and NBI, if Ip ramp-up were successful • Diagnostics adjusted for start-up plasmas at low Ip and ne