Progress of Gyrotron Development for ITER

Progress of Gyrotron Development for ITER Presented by A. Kasugai (JAEA) The report includes materials of three papers: Demonstration of 1MW quasi-cw Operation of 170GHz Gyrotron and Progress of Technology for ITER (FT/3-1Ra) A. Kasugai, K. Sakamoto, K. Takahashi, K. Kajiwara, Y. Oda, N. Kobayashi Japan Atomic Energy Agency, Japan Status of Development in Russia of Megawatt Power Gyrotrons for Fusion (FT/3-1Rb) G.G.Denisov 1), A.Litvak 1), V.E.Myasnikov 2), E.M.Tai 2), V.I.Ilin 3) 1) Institute of Applied Physics, 2) GYCOM Ltd., 3) Kurchatov Institute Experimental Investigations on the Pre-Prototype of the 170GHz, 2MW Coaxial Cavity Gyrotron for ITER (FT/3-1Rc) T. Rzesnicki 1), B. Piosczyk 1), J. Flamm 2), J. Jin 1), S. Kern 1), O. Prinz 1), M. Thumm 1,2) 1) Forschungszentrum Karlsruhe, 2) Universiat Karlsruhe, Institut fur Hochstfrequenztechnik und Elektronik

EC Heating & Current Drive for ITER ITER ITER Requirement Electron Cyclotron Heating & Current Drive / Instability Suppression Total Injection Power: 20MW (upgradable to 40MW) Pulse Duration: > 400s (burning phase), 3600s (CW operation phase) RF Source High Power Gyrotron 24-Gyrotrons in ITER are delivered by 3-parties Target of ITER Gyrotron Development: 170GHz, >1MW, >500s, >50% Cylindrical Cavity Gyrotron Coaxial Cavity Gyrotron

170GHz High Power Gyrotron Gyrotron: microwave tubes that utilizes electron cyclotron resonance maser (CRM) Collector Electron beam Output Window Technical Issues Higher Mode Oscillation for High Power Output window for Long Pulse Operation Energy Recovery for High Efficiency Height : ~3m Weight : ~800kg RF beam Electron Gun Mode Converter Cavity Superconducting Magnet

Progress of Gyrotron Technologies Breakthrough Technologies 170GHz ITER Gyrotron (1) Higher Order Mode Cavity Demonstration of 170GHz/ 1MW Oscillation by Cylindrical & Coaxial Cavity (2) Energy Recovery using Depressed Collector Efficiency 30% 50% (3) Synthesized Diamond Output Window Low loss tangent & High thermal Conductivity (4) High Efficiency Mode Converter Cavity mode Gaussian Beam >98% Efficiency Suppression of Stray RF & Outgas

Gyrotron Development in EU 2006 Full Performance for W7-X demonstrated: 140GHz/0.92MW/1800s Cylindrical Cavity with TE28,8 Development of Advanced Gyrotron for 2MW Oscillation for ITER. Coaxial Cavity Gyrotron

22nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland! Advanced Gyrotron using Coaxial Cavity! Coaxial Cavity! Based on Success of 165GHz coaxial Cavity The prototype of 170GHz coaxial gyrotron (TE34,19 mode) for ITER! Electron Gun! Inner Rod Inserted in Large Cylindrical Cavity! Inner Rod in Cavity! Suppression of! Mode Competition! Beam Energy Depression! 165GHz : 2.2MW/ 1ms (FZK)!! Proof of 2MW gyrotron! 170GHz /1.4MW /24% /short pulse! (under experiment)!!

Development of Russian Gyrotrons Modification of Kurchatov test stand. New evacuated transmission line /load was fabricated and assembled in 2007. TE25,10 High Power Gyrotron 0.85MW/203s 1.02MW/116s (Test Stand Limitation) IAP RAS GYCOM INF Other Gyrotrons Results Frequency Tunable: 105-140GHz/0.9MW/10s (for ASDEX-U) Long Pulse: 84GHz/0.2MW/1000-3900s (for LHD) High Efficiency: 75GHz/0.8MW/0.1s/70% (for General physics Institute)

Advanced High Power Gyrotron High Power Oscillation using Cylindrical Cavity with Higher Mode Power (MW) & Pitch Factor (Test Result) Pitch Factor Power~2MW Oscillation Efficiency ~33% Beam Current (A) Recent Result of Advanced Gyrotron 170GHz/1.4MW/ 41% /0.1s 170GHz/1.5 2.0MW/0.1ms Efficiency Prototype TE28,12 Short Pulse TE31,12 (2005) 170GHz/1.6MW/1ms Long Pulse Exp. soon Demonstration of Stable High Power Oscillation

Output Power (MW) Output Power (MW) Output Power (MW) Output Power (MW) 1.0 TE31,8 damps 1.0E+3 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0.01 0.0 0.8 0.6 0.4 0.4 0.2 0.2 a b TE30,8 TE30,8 TE31,8=main mode (Single-mode simulation) TE31,8 0.00 6.6 6.62 6.64 6.66 6.68 6.7 6.60 6.6262 6.6464 6.66 66 6.68 68 6.70 Cavity Field B c (T) Power (kw) 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Adjacent Mode Helps Excitation of Main Mode 56% (Experiment) 167GHz Hard Excitation Soft Excitation adjmode adjmode Hard Excitation (mismatch of oscillation condition ) Power (kw) 1.0E+2 1.0E+1 1.0E+0 1.0E-1 1.0E-2 0 2 4 6 8 10 1.0E+3 1.0E+2 1.0E+1 1.0E+0 1.0E-1 Main mode Time (ns) adjmode TE30,8 (Two-modes simulation) TE30,8 TE31,8 When TE30,8 exist, TE31,8 can grow. Parasitic mode M-mode suppress adj-mode. TE31,8 Single mode oscillation TE31,8 mode is robust in the hard excitation region. 0 100 200 300 400 500 Time (ns) K.Sakamoto, et al., Nature Phys., 3(2007)411.

Demonstration of ITER Requirement V-CPD (+24.5kV) V-Anode (-6.3kV) V-Cathode (-48.3kV) Beam Current (38A) Pout (1.01MW) 800s (>1MW) Long pulse at Hard Excitation No saturation 60% 1MW Power Total Effi. Osci. Effi. Cavity Field (6.625T) Collector Temp (~100 C) Arc signal (a.u.) Vacuum Pressure (max. 8x10-8 torr) Oscillation Time (s) Vacc.=~72kV, Vanode=optimized, VCPD=optimized, Cavity Field=Optimized Current was kept I c <40A, to simulate the ITER power supply. Active control of Cavity field, anode voltage, heater power has been performed to access maximum point at hard excitation. Achievement of 1MW/800s/55%

Arc signal (0.8MW) Cooling water for Input : 42 º.C pressure~1.5x10-7 torr 3600s 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Stable and Reliable Operation Quasi-CW operation Stable 1hr/0.8MW/57% V-CPD V-anode V-cathode Beam current (~31A) RF signal Cavity field (6.62T) The achievement is a great step in the progress of the ITER Project Output energy (GJ) 200 100 0 Demonstration of ITER criteria (1MW/800s/55%) 0s/55 1 hr 0.6MW/ 45% 0.8MW/1hr/57% Repetitive Operation Demonstration of 56% in hard excitation region 0 10 20 30 (April,2006) Time (Month) Total output energy reached to 190 GJ for >2 years operation.

170GHz ITER Gyrotron 1MW/ 800sec / 55% 0.8MW/ 1hr/ 57% Hard Excitation (FT/3-1Ra) Advanced Gyrotron for ITER Cylindrical Cavity TE28,12 1.5-2MW /0.1msec (FT/3-1Rb) Coaxial Cavity TE34,19 1.4MW /a few msec (FT/3-1Rc) 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Summary Requirement of ITER Gyrotron Before EDA 100 200 300 400 Power (MW) 1.0 0.8 0.6 0.4 0.2 10 20 30 Gyrotron Progress 40 50 500 Efficiency (%) Pulse Duration (s)

170GHz ITER Gyrotron 1MW/ 800sec / 55% 0.8MW/ 1hr/ 57% Hard Excitation (FT/3-1Ra) Advanced Gyrotron for ITER Cylindrical Cavity TE28,12 1.5-2MW /0.1msec (FT/3-1Rb) Coaxial Cavity TE34,19 1.4MW /a few msec (FT/3-1Rc) 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Summary Achievement of Performance Requirement of ITER Gyrotron Before EDA 100 200 300 400 Power (MW) 1.0 0.8 0.6 0.4 0.2 10 20 30 Gyrotron Progress 40 50 500 Efficiency (%) Pulse Duration (s)

170GHz ITER Gyrotron 1MW/ 800sec / 55% 0.8MW/ 1hr/ 57% Hard Excitation (FT/3-1Ra) Advanced Gyrotron for ITER Cylindrical Cavity TE28,12 1.5-2MW /0.1msec (FT/3-1Rb) Coaxial Cavity TE34,19 1.4MW /a few msec (FT/3-1Rc) 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Summary Achievement of Performance Requirement of ITER Gyrotron Before EDA 100 200 300 400 Power (MW) 500 Efficiency (%) Pulse Duration (s) Demonstrated ITER Relevant Gyrotron 1.0 0.8 0.6 0.4 0.2 10 20 30 Gyrotron Progress 40 50

170GHz ITER Gyrotron 1MW/ 800sec / 55% 0.8MW/ 1hr/ 57% Hard Excitation (FT/3-1Ra) Advanced Gyrotron for ITER Cylindrical Cavity TE28,12 1.5-2MW /0.1msec (FT/3-1Rb) Coaxial Cavity TE34,19 1.4MW /a few msec (FT/3-1Rc) 22 nd Fusion Energy Conference, 12-18,Oct., 2008, Geneva, Switzerland Summary Achievement of Performance Requirement of ITER Gyrotron Before EDA 100 200 300 400 Power (MW) 500 Efficiency (%) Pulse Duration (s) Demonstrated ITER Relevant Gyrotron Great Step for ITER Construction 1.0 0.8 0.6 0.4 0.2 10 20 30 Gyrotron Progress 40 50