13th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating Nizhny Novgorod, Russia May 17-20, 2004 РАН Low Frequency Gyrotrons for Fusion НПП ГИКОМ V.E. Zapevalov, Yu.K. Kalynov, V.K. Lygin, O.V. Malygin, S.A. Malygin, M.A. Moiseev, V.N. Manuilov, V.I. Khizhnjak, E.A. Solujanova, E.M. Tai (IAP RAS, GYCOM Ltd., Nizhny Novgorod)
Outline Introduction Design Features Cavity modes Electron gun Quasi-optical mode converter Experiments Conclusion
Introduction For some experimental plasma set-ups powerful RF sources with frequency from 5 GHz up to 30 GHz are requested. The report presents the results of the low frequency powerful gyrotrons development in Russia. Test results for 5GHz/0.5 MW and 28GHz/0.5MW gyrotrons are presented. Several design versions of 5 GHz, 17.5 GHz and 28 GHz gyrotrons with output power 0.5-1 MW, its specific property details, special technical problems and test set-up are discussed.
DIFFERENCE of mm and cm Gyrotrons Problem mm cm 1 mode selection + 2 cavity heat loading + 3 electron beam + initial velocity spread + Non adiabatic effects 4 mode converter + + + 5 collector + + + 6 window +
5GHz/500kW/1s Gyrotron Operating mode ТЕ 0,1 Wavelength 60 mm Electron energy 70 kev Beam current 25 A Pulse duration 1 s Efficiency 30 % Output power 500 kw
5GHz/500kW/1s Gyrotron DIODE-TYPE MAGNETRON INJECTION GUN Beam voltage 70 kv Operating beam current 25 A Cathode radius 45 mm Beam radius at cavity 25.6 mm Emitter current density 2 A/cm 2 Pitch-factor 1.3
5GHz/500kW/1s Gyrotron DIODE-TYPE MAGNETRON INJECTION GUN R/Rc 2 1 0-2 -1 1 2 3 4 5 6 7 Z/Rc
5GHz/500kW/1s Gyrotron The velocity spread and average oscillatory energy vs. beam parameters 1.0 EPOSR 0.8 t EPOS-V 0.6 0.4 0.2 0 10 20 30 40 BEAM CURRENT, A
5GHz/500kW/1s Gyrotron Profile of the cavity and distribution of an electromagnetic field. R, mm 50 45 40 35 30-200 -100 0 100 200 300 400 500 Z, mm
5GHz/500kW/1s Gyrotron Calculated power and efficiency v.s beam current at various pitch-factors 1.0 0.8 g=1.3 efficiency P, MW 0.5 0.4 POWER, MW 0.6 0.4 0.2 1.2 1.1 1 0.3 0.2 0.1 EFFICIENCY 0 10 20 30 40 BEAM CURRENT, A
5GHz/500kW/1s Gyrotron REPITER The repeater was carried out as the shielding slot of a circular waveguide. The conic collector was interfaced to the cylindrical screen of the repeater, and the electronic beam was deduced on a collector through a ring crack between the screen and a target waveguide. Such schema of division of an electromagnetic wave and electron beam has allowed reducing considerably length of gyrotron.
R, mm 150 5GHz/500kW/1s Gyrotron COLLECTOR 100 50 0 450 500 550 600 650 700 750 800 Z, mm 2.5MW / 1c
5GHz/500kW/1s Gyrotron MAGNETIC SYSTEM (Criomagnet) Height (max) 1150 mm Diameter (max) 650 mm Diameter of a warm aperture 205 mm Length of a warm aperture 760 mm Capacity helium tank 71 liter Capacity nitric tank 50 liters Working current 22 A
5GHz/500kW/1s Gyrotron MAGNETIC SYSTEM (Solenoid ) External diameter 400 mm Internal diameter 205 mm Length 650 mm Weight 300 kg Power 5.5 kw Working current 86 A
5GHz/500kW/1s Gyrotron Calculated and measured power and efficiency v.s beam current 1.0 0.8 efficiency P, MW 0.5 0.4 POWER, MW 0.6 0.4 0.3 0.2 EFFICIENCY 0.2 0.1 0 10 20 30 40 BEAM CURRENT, A
28GHz/500kW/0.1s Gyrotron General view and main parameters Operating mode ТЕ 4,2 collector Frequency 28 GHz window output power Electron energy 70 kev 1700 500 Beam current 20 A cavity center 316 Pulse duration 0.1 s 139 Efficiency 36 % cathode insulator 575 Output power 500 kw
28GHz/500kW/0.1s Gyrotron DIODE-TYPE MAGNETRON INJECTION GUN Beam voltage 70 kv Nominal beam current 20 A Cathode radius 21.5 mm Beam radius in cavity 7 mm Density of emitter current 2.5 A/cm 2 Pitch-factor 1.3
28GHz/500kW/0.1s Gyrotron Measured Power and Efficiency v.s Beam Current
17.5GHz/1MW/5s Gyrotron Project Design modes mode TE 4,2,1 TE 5,2,1 TE 1,3 ν 9.28 10.52 8.54 R cav, mm p ohm, 25.35 28.70 23.30 0.34 0.30 0.27 kw/cm 2
17.5GHz/1MW/5s Gyrotron Project Mode Converter Gaussian beam rotating TE 1.3 mode standing TE 1.3 mode visor cavity weak elliptic taper parabolic mirror
17.5GHz/1MW/5s Gyrotron Project Gyrotron output parameters 0.5 η TE 1.3, 17.5 GHz, Q=494, Uo=100 kv, dv =0 T P, MW 0.4 g=1.3 1.6 0.3 1.2 1.3 1.2 0.2 1.1 1.2 1.1 0.8 g=1 g=1 0.1 0.4 I, A 0 10 20 30 40
17.5GHz/1MW/5s Gyrotron Project MAGNETRON INJECTION GUN 2.5 R/Rc 2.0 1.5 1.0 0.5 Z/Rc -2-1 0 1 2 3 4 5 6 7
17.5GHz/1MW/5s Gyrotron Project MAGNETRON INJECTION GUN 1.0 EPOSR 7.0 f(v ) I = 30 A PARAMETERS OF BEAM 0.8 0.6 0.4 t EPOS-V 6.0 5.0 4.0 3.0 2.0 I = 40 A I = 50 A Uo = 90 kv 0.2 1.0 0 10 20 30 40 50 BEAM CURRENT (А) 0.4 0.5 0.6 0.7 0.8 0.9 v
17.5GHz/1MW/5s Gyrotron Project COLLECTOR SISTEM Trajectories without space charge in the system. Trajectories with space charge in the system.
17.5GHz/1MW/5s Gyrotron Project COLLECTOR SISTEM P max P = 1.73kW/cm 2 max = 1.76kW/cm 2 Z max Z max = = 80.62cm 79.35cm Longitudinal heat load density distribution without space charge calculation Longitudinal heat load density distribution with space charge calculation
17.5GHz/1MW/5s Gyrotron Project COLLECTOR SISTEM Collector with 150 mm radius P max = 0.45Kw/cm 2 Z max = 86.91cm Electron trajectories in optimal version. Heat lode distribution in optimal case.
28GHz/1MW/5s Gyrotron Project Design modes mode TE 5,2,1 TE 6,2,1 TE 7,2,1 ν 10.52 11.73 12.93 R cav, mm 17.95 20 22.05 p ohm, 0.44 0.40 0.36 kw/cm 2
28GHz/1MW/5s Gyrotron Project Gyrotron output parameters 0.5 η TE 6.2, 28 GHz, Q=683, Uo=100 kv, dv =0 T P, MW 0.4 g=1.3 1.6 0.3 1.2 1.3 1.2 0.2 1.1 g=1 1.2 1.1 g=1 0.8 0.1 0.4 I, A 0 10 20 30 40
28GHz/1MW/5s Gyrotron Project MAGNETRON INJECTION GUN 2.5 R/Rc 2.0 1.5 1.0 0.5 Z/Rc -2-1 0 1 2 3 4 5 6 7 8
28GHz/1MW/5s Gyrotron Project MAGNETRON INJECTION GUN 1.0 EPOSR 7.0 f(v ) I = 30 A PARAMETERS OF BEAM 0.8 0.6 0.4 t 28 GHz Uo = 90 kv Rc = 38.5 mm EPOS-V 6.0 5.0 4.0 3.0 2.0 28 GHz Uo = 90 kv Rc = 38.5 mm I = 40 A I = 50 A 0.2 1.0 0 10 20 30 40 50 BEAM CURRENT (А) 0.4 0.5 0.6 0.7 0.8 0.9 v
28GHz/1MW/5s Gyrotron Project Gyrotron output parameters 0.5 η TE 6.2, 28 GHz, Q=683, Uo=100 kv, dv =0 T P, MW 0.4 g=1.3 1.6 0.3 1.2 1.3 1.2 0.2 1.1 g=1 1.2 1.1 g=1 0.8 0.1 0.4 I, A 0 10 20 30 40
Conclusion Low frequency powerful gyrotrons development in Russia is presented. The 0.5 MW/01s regime is shown at operating frequencies. Several design versions of 5 GHz, 17.5 GHz and 28 GHz gyrotrons with output power 0.5-1 MW, its specific property details are presented. Main and special technical problems of lowfrequency gyrotron and test set-up are are outlined and discussed. The long pulse and CW versions of lowfrequency gyrotron are under construction now.