PRESENT STATUS OF THE NEW MULTI-FREQUENCY ECRH SYSTEM FOR ASDEX UPGRADE

Transcription

1 Max-Planck-Institut für Plasmaphysik PRESENT STATUS OF THE NEW MULTI-FREQUENCY ECRH SYSTEM FOR ASDEX UPGRADE D. Wagner, G. Grünwald, F. Leuterer, A. Manini, F. Monaco, M. Münich, H. Schütz, J. Stober, H. Zohm, T. Franke Max-Planck-Institut für Plasmaphysik, D Garching, Germany 1,3 M. Thumm, 2 R. Heidinger, 1 G. Gantenbein, 2 A. Meier Forschungszentrum Karlsruhe, 1) Institut für Hochleistungsimpuls- und Mikrowellentechnik, 2 Institut für Materialforschung I, D Karlsruhe, Germany 3 Universität Karlsruhe, Institut für Höchstfrequenztechnik und Elektronik, D Karlsruhe, Germany W. Kasparek, C. Lechte Institut für Plasmaforschung, Universität Stuttgart, D Stuttgart, Germany A. Litvak, G. Denisov, Institute of Applied Physics, RAS, Nizhny Novgorod, Russia E.M. Tai, L.G. Popov, V.O. Nichiporenko, V.E. Myasnikov, E.A. Solyanova, SA. Malygin GYCOM Ltd, 46 Ulyanov St., Nizhny Novgorod, , Russia

2 MULTI-FREQUENCY ECRH SYSTEM PARAMETERS physics aims: heating and current drive in advanced tokamak regime for feedback controlled suppression of neoclassical tearing modes, pressure profile and transport

3 EXTENSION OF ECRH OPERATING SPACE

4 EXTENSION OF ECRH OPERATING SPACE 4 frequencies are enough to open up a wide operating space allows deposition inside ρ = 0.25 between 1.7 T < B t < 2.6 T for 1 MA, this corresponds to 2.9 < q95 < 4.2

5 MULTI-FREQUENCY ECRH SYSTEM PARAMETERS physics aims: frequency: power: heating and current drive in advanced tokamak regime for feedback controlled suppression of neoclassical tearing modes, pressure profile and transport 105 and 140 GHz as 2-f-gyrotron, 105 / 117 / 127 / 140 GHz as m-f-gyrotron (step tunable) frequency set between pulses 4 MW/ 10 sec at 140 GHz 3.2 MW / 10 sec at other frequencies provided by 4 gyrotrons

6 STATUS AND PERSPECTIVE OF NTM STABILIZATION WITH CW-ECCD present experiments: deposition width < island size ITER: Deposition width > island size Driving helical current within the island is relevant O-point modulation of co-eccd

7 PHASE LOCKED MODULATED ECCD O-point phased co-eccd X-point phased co-eccd O-point alligned M-ECCD: CD driven helically within the island, high efficiency X-point alligned M-ECCD: CD mostly outside the island destabilizing

8 MULTI-FREQUENCY ECRH SYSTEM PARAMETERS physics aims: frequency: power: modulation: transmission: launcher: heating and current drive in advanced tokamak regime for feedback controlled suppression of neoclassical tearing modes, pressure profile and transport 105 and 140 GHz as 2-f-gyrotron, 105 / 117 / 127 / 140 GHz as m-f-gyrotron (step tunable) frequency set between pulses 4 MW/ 10 sec at 140 GHz 3.2 MW / 10 sec at other frequencies provided by 4 gyrotrons up to 25 khz 87 mm HE11-waveguides, normal air, length ~ 70 m feedback controlled deposition via poloidal launching angle, toroidal angle set between pulses

9 STEP-TUNABLE HIGH-POWER GYROTRONS 2-frequency GYCOM Gyrotrons Odissey-1, Odissey-2 depressed collector U cath -60kV U body +30kV I beam 40A performance at IPP: single disc window resonant at 105 GHz and 140 GHz pulse length = 10 s Vid9_GY1_140_W_10sb_MPEG4.avi Gyrotron Odissey-1 currently being equipped with CVD diamond Brewster window conversion to multi-frequency gyrotron with 2 additional frequencies between GHz

10 Brewster window BROADBAND GYROTRON OUTPUT WINDOW TM polarization TE polarization only broadband for defined linear polarization A gyrotron with BN-Brewster window was successfully tested at GYCOM with 11 frequencies ( GHz), powers of MW, and pulses of msec

11 GYROTRON ARRANGEMENT WITH CENTRAL HIGH POWER LOAD

12 IMPROVED GYCOM HIGH-POWER LOAD new stainless steel high-power load after some conditioning very good performance at both frequencies! 1.9m 0.66m Vid8_GY1_140_L_10sb_MPEG4.avi

13 MATCHING OPTICS UNIT to HE11 line polarizer 1 phase correcting mirrors gyrotron central load spherical short load pulse load 1 MW, 1 s (CNR Milano) polarizer 2 (design IPF Stuttgart)

14 HE 11 TRANSMISSION LINE Estimated losses frequency 105 GHz 140 GHz Ohmic loss (70 m HE11 waveguide) 0.12% 0.05% Ohmic loss (8 miter bends) 0.76% 1.03% Diffraction loss (8 miter bends) 5.28% 3.43% Atmospheric absorption (L=70m) 1.2% 3.17% Corrugated HE 11 waveguide, I.D.=87mm (normal air) total loss 7.36% 7.68% Measured total loss frequency 105 GHz 140 GHz lower transmission losses probably due to better alignment TL1 with Odissey-1 TL1 with Odissey-2 12% 5% 10% 8%

15 HE 11 TRANSMISSION LINE Estimated losses frequency Ohmic loss (70 m HE11 waveguide) Ohmic loss (8 miter bends) Diffraction loss (8 miter bends) Atmospheric absorption (L=70m) total loss 105 GHz 0.12% 0.76% 5.28% 1.2% 7.36% 140 GHz 0.05% 1.03% 3.43% 3.17% 7.68% measured mode pattern at waveguide input Measured total loss frequency 105 GHz 140 GHz lower transmission losses probably due to better alignment TL1 with Odissey-1 TL1 with Odissey-2 12% 5% 10% 8%

16 MODULATION OF ODISSEY-1 On / off modulation possible up to 1 khz. Fast analog modulation of U cath only with constant U body up to 25 khz U body = kv U cath I beam f mod = 25 khz U cath = -42 kv <-> -25 kv I body U det Pulse length 100 msec 2 different time scales: 20 msec/div and 50 µsec/div

17 FREQUENCY DRIFT OF ODISSEY-1 - measured frequency drift ~120 MHz - 80 MHz within 50 msec Possible reasons: - voltage rise time - build up of background plasma in the cavity - thermal expansion of the cavity

18 FREQUENCY DRIFT OF ODISSEY GHz P=560 kw on/off (digital) modulation measurements by: F. Meo, J. Holm (EURATOM-Risø) P. Woskov (PSFC, MIT)

19 FREQUENCY DRIFT OF ODISSEY GHz 120/560 kw Ucath (analog) modulation measurements by: F. Meo, J. Holm (EURATOM-Risø) P. Woskov (PSFC, MIT)

20 BROADBAND TORUS WINDOW double disc window Reflection, d 1 =d 2 = mm distance = 15 mm distance = 10 mm distance = 5 mm power (%) frequency Reflection (GHz) 5 - polarization independent - minimum bandwidth at Fabry-Perot resonances must include frequency drift of the gyrotron - needs evacuation power (%) distance = 15 mm distance = 10 mm distance = 5 mm frequency (GHz)

21 DOUBLE-DISC WINDOW (design and construction: FZK Karlsruhe)

22 DOUBLE-DISC WINDOW COLD TEST Calculated - Disc distance mm Measured Vacuum (room temperature) 0-10 Reflexion / db Frequency / GHz

23 FAST STEERABLE LAUNCHER ECRH launching mirrors in sector 5 launcher mirrors: Cr / Cu / Au - coated graphite A poloidal angle variation of 10 in 100 msec has been achieved

24 FAST STEERABLE LAUNCHER High-Power test of the coated graphite mirror at IPP Greifswald using a 140 GHz Gyrotron with up to 750kW, τ=20s, w o = 30mm, ϑ inc =57 IR pictures: during the pulse 20s after the pulse Example 20 sec pulse at 720 kw: temperature at the mirror edge: at start: 23 C, at 10 sec during pulse: 58 C, at 20s after pulse: 46 C No deterioration of the mirror surface was found

25 FAST STEERABLE LAUNCHER ANSYS simulation by A. Encheva, EPFL Lausanne T / C T=10 s T max =347 C

26 FAST STEERABLE LAUNCHER ANSYS simulation by A. Encheva, EPFL Lausanne T / C 20s after pulse

27 SUMMARY AND OUTLOOK Reliable long pulse gyrotron operation at 105 and 140 GHz, also with modulation up to 25 khz frequency drift during a gyrotron pulse within the limit for future double disc window application New long-pulse high-power load Low transmission line losses at both freqencies launcher mirror tests successful gyrotron Odissey-1 equipped with Brewster window First plasma shots with Odissey-2