Development in Russia of High-Power Gyrotrons for Fusion

Institute of Applied Physics, Nizhny NovgorodGYCOM Ltd., Nizhny NovgorodKurchatov Institute, Moscow

G.G.DenisovG.G.DenisovG.G.DenisovG.G.Denisov, , , , A.G.LitvakA.G.LitvakA.G.LitvakA.G.Litvak, , , , V.E.MyasnikovV.E.MyasnikovV.E.MyasnikovV.E.Myasnikov, , , , E.M.TaiE.M.TaiE.M.TaiE.M.Tai, , , , V.I.IlinV.I.IlinV.I.IlinV.I.Ilin

Vienna, 6-8 June , 2007

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Three lines of Three lines of Three lines of Three lines of gyrotrongyrotrongyrotrongyrotron development:development:development:development:“RoutineRoutineRoutineRoutine”””” fabrication of fabrication of fabrication of fabrication of gyrotronsgyrotronsgyrotronsgyrotrons for ECRH customersfor ECRH customersfor ECRH customersfor ECRH customers

2222----4/year4/year4/year4/year

Development of Development of Development of Development of gyrotrongyrotrongyrotrongyrotron for ITERfor ITERfor ITERfor ITER

R&D of advanced R&D of advanced R&D of advanced R&D of advanced gyrotronsgyrotronsgyrotronsgyrotrons(multi-frequency, multi-megawatt)

Russian Russian Russian Russian gyrotronsgyrotronsgyrotronsgyrotrons for fusionfor fusionfor fusionfor fusion

CVD diamond window technology developmentCVD diamond window technology developmentCVD diamond window technology developmentCVD diamond window technology developmentand moreand moreand moreand more

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There are two presentations on gyrotron/windows (June 7)

First paperFirst paperFirst paperFirst paper presents presents presents presents � Status of Status of Status of Status of gyrotrongyrotrongyrotrongyrotron development ITERdevelopment ITERdevelopment ITERdevelopment ITER� Discussion on Discussion on Discussion on Discussion on gyrotrongyrotrongyrotrongyrotron power enhancementpower enhancementpower enhancementpower enhancement� Some problems of multiSome problems of multiSome problems of multiSome problems of multi----frequency frequency frequency frequency gyrotrongyrotrongyrotrongyrotron developmentdevelopmentdevelopmentdevelopment

Second paperSecond paperSecond paperSecond paper contents materials oncontents materials oncontents materials oncontents materials on� CVD diamond window technology developmentCVD diamond window technology developmentCVD diamond window technology developmentCVD diamond window technology development

Delivered to TEXTOR100.8 MW140 GHz

**New design, TE28.120.1**1.44 MW**170 GHz

11 frequencies**New high-eff. mode converter

0.110-4

0.7 – 0.9 MW1.2 MW

105 -140 GHz*105-140 GHz**

4 tubes , delivered to SWIP, China10.5MW68 GHz

2 tubes delivered to ASDEX-Up10 0.8 - 0.9 MW105 / 140 GHz

Delivered to G Ph I70% eff. , 99% Gaussian0.10.8 MW75 GHz

For ITER project101300

0.95 MW0.64 MW170 GHz

NotePulse, secPowerFrequency

MW power level gyrotrons developed and tested in 2005-2007

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Test stand for 170 GHz/ 1MW Gyrotron at KI

PlanPlanPlanPlan viewviewviewview RightRightRightRight----side side side side viewviewviewview

Gyrotron & MOUGyrotron & MOUGyrotron & MOUGyrotron & MOU MTPMTPMTPMTP

LoadLoadLoadLoad

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2006: 60kV + 30 kV, 40A, 100 sec2006: 60kV + 30 kV, 40A, 100 sec2006: 60kV + 30 kV, 40A, 100 sec2006: 60kV + 30 kV, 40A, 100 sec2007: 70 kV +30 kV, 100A, 1000 sec2007: 70 kV +30 kV, 100A, 1000 sec2007: 70 kV +30 kV, 100A, 1000 sec2007: 70 kV +30 kV, 100A, 1000 secand 60kV + 30 kV, 23 A, CW at Nizhny Novgorodand 60kV + 30 kV, 23 A, CW at Nizhny Novgorodand 60kV + 30 kV, 23 A, CW at Nizhny Novgorodand 60kV + 30 kV, 23 A, CW at Nizhny Novgorod

MOUMOUMOUMOU

LOADLOADLOADLOAD

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New Water-Cooled Load

Test stand for 170 GHz/ 1MW Gyrotron

Matching Optic Unit

(2006)(2006)(2006)(2006)

Gaussian modeGaussian modeGaussian modeGaussian modeOutput radiation

170170170170±±±±0.50.50.50.5 GHzGHzGHzGHzFrequencyTE 25.10Operating mode< 6.9 TCavity magnetic field

ValueDesign parameter

50 %50 %50 %50 %Efficiency in TEM 00 mode27-30 kVVoltage depression80-mm (106mm)Window, CVD Diamond

400/3600 s400/3600 s400/3600 s400/3600 sPulse duration

40 - 50 ABeam current70 - 80 keVBeam energy

170 GHz/1MW GYROTRON FOR ITER170 GHz/1MW GYROTRON FOR ITER170 GHz/1MW GYROTRON FOR ITER170 GHz/1MW GYROTRON FOR ITERIAPIAPIAPIAPIAPIAPIAPIAPIAPIAPIAPIAPGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOM

oil

output radiation

mirrors

cavity

anodeCathode voltage Retardingvoltage

Water cooling underretarding potential

Beam acceelerating voltage

Worked-out electron beam

TE25.10

Operating modeOutputwave beam

Improved mode converter for 170 GHz Improved mode converter for 170 GHz Improved mode converter for 170 GHz Improved mode converter for 170 GHz gyrotrongyrotrongyrotrongyrotron

HHHHzzzz field component distributionfield component distributionfield component distributionfield component distributionat the launcher wall at the launcher wall at the launcher wall at the launcher wall

z

ϕ

Field amplitude and phase Field amplitude and phase Field amplitude and phase Field amplitude and phase distribution at the gyrotron windowdistribution at the gyrotron windowdistribution at the gyrotron windowdistribution at the gyrotron window

Aperture=120x120mm2

Gaussian mode contentGaussian mode contentGaussian mode contentGaussian mode content: : : : η=99,=99,=99,=99,5555 %%%%((((AxAxAxAx=14.92=14.92=14.92=14.92мммммммм, , , , AyAyAyAy=14.58=14.58=14.58=14.58мммммммм))))Total diffraction lossesTotal diffraction lossesTotal diffraction lossesTotal diffraction losses: : : : ∆P < P < P < P < 2222% % % %

•PrePrePrePre----shapingshapingshapingshaping•Slightly conical launcherSlightly conical launcherSlightly conical launcherSlightly conical launcher•Profiled mirrorsProfiled mirrorsProfiled mirrorsProfiled mirrors

IAPIAPIAPIAPIAPIAPIAPIAPIAPIAPIAPIAPGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOMGYCOM

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100 second pulse of the 170 GHz gyrotron

Gyrotronefficiency 53% !

I cath , 1V => 10A

U cath, 1V => 20кVU rec , 1v => 10кV

IIII anodanodanodanod,,,, 1v1v1v1v ====> > > > 55550m0m0m0mА

UbeamUbeamUbeamUbeam = 7= 7= 7= 73333 kVkVkVkVUrecUrecUrecUrec = 2= 2= 2= 27777 kVkVkVkVI = 38.5 AI = 38.5 AI = 38.5 AI = 38.5 AP = 950 kWP = 950 kWP = 950 kWP = 950 kW

Detector signalDetector signalDetector signalDetector signal

020

4060

80100

120

0 100 200 300 400 Pulse duration, sec

520 kW520 kW520 kW520 kW640 kW640 kW640 kW640 kW950 kW950 kW950 kW950 kW

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Gyrotron limitation: heating of the collector ceramics

No-cooling was applied

Cooling system will be implemented

in 2007

P ~ 2kW

The gyrotron was open after the tests and no damages were found

� Test of cryomagnet with 190-mm bore and magnetic field7.3 T in 2005 (+)

� Construction of 100-120 kV/50-70 A/ CW power supply in 2007� Design completed of 1.5/ 1.7-MW gyrotron (+)

• TE TE TE TE 28.1228.1228.1228.12 operating mode of conventional cavity• diode electron gun • internal mode converter with diffraction losses less than 3 %• collector withstanding up to 4-MW beam power in short pulses

� Test of a short-pulse model (100 ms) in 2005 (+)� Fabrication and test of an industrial prototype in 2006 (+)� Fabrication of a long-pulse tube in 2007

STEPS TOWARD 1.5 MW GYROTRONSTEPS TOWARD 1.5 MW GYROTRONSTEPS TOWARD 1.5 MW GYROTRONSTEPS TOWARD 1.5 MW GYROTRON

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170 GHz/1.5 MW gyrotron prototype

-4 -2 0 2 4

0.0000

0.0005

0.0010

Gm.p

f , %δ

28.12-27.13

-28.13-25.13-26.13

-24.13

29.1227.12

28.1126.12

30.12

Ro=8.265

� Cylindrical Cavity Mode Cylindrical Cavity Mode Cylindrical Cavity Mode Cylindrical Cavity Mode ТЕТЕТЕТЕ 28.1228.1228.1228.12� Cavity diameter 41.5 mm� Peak thermal load 1.35 kW/cm2� Beam voltage 100 kV� Beam current 50-55 A� Interaction efficiency 30-33%(without DC)

Spectrum of the cavity Eigenfrequencies & coupling factors for different modes of 1.5MW gyrotron

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89 90 91 92 93 94

Beam voltage, kV

800

900

1000

1100

1200

1300

1400

1500

Powe

r, kW

0.3

0.32

0.34

0.36

0.38

0.4

0.42

0.44

Effic

iency

170GHz/1.5MW gyrotron with TE28.12 operating modeOutput power and gyrotron efficiency vs. beam voltage

Short pulse (0.1 sec)

model tests

SC magnet

Collector Coils

BN Window

170 GHz/ 1.5 MW GYROTRONRF BEAM AT THE WINDOW PLANE

Field amplitude and phase distribution

Gaussian mode content – 98.2%Ax=23.1 mm Ay=22.6 mm

Wave beam image on the thermal paper

Stray radiation less then 2%

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� Very advanced gyrotron components required (not shown yet)- Mode converter (

Multi-frequency gyrotron. Main problems.(changing the main magnetic field a gyrotrontypically can operate at different frequencies.Very attractive for advanced ECW systems)

• Effective gyrotron operation at different modes• Effective conversion of all modes into Gaussian beam

• Tuneable or broadband window

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Design requirements for the multi-frequency gyrotronfor ASDEX

� Frequency range (at least 4 frequencies) 105 – 140 GHz� Output power:

at frequency 140 GHz 1 MWat frequency 105 GHz 0.8 MWat intermediate frequencies 0.8 MW

� Pulse duration 10 s� Maximal beam voltage 90 kV� Maximal beam current 50 A� Efficiency with energy recovery 40-50%� Output radiation Gaussian beam

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Long-pulse (10 sec) test results of two-frequency gyrotrons

Anode current, mA

Current,A

Voltage, kV

Efficiency, %

PowerTotal/

Gaussian, kW

Frequency,GHz

New mode converter for multi-frequency gyrotron 1MW/105…140 GHz

140 mm

Waveguide deformation ∆R( φ,z): ±0,31 mm

TE 17 6f=104.8 GHz

TE 20 7f=124.0 GHz

TE 22 8f=139.8 GHz

The new converter was successfully tested at 6 modes (!)

April 2006

Test of the improved mode converter in gyrotronShort pulse (100 µsec) mock-up of the multi-frequency gyrotron was tested at 6 different modes (frequencies from 105 up to 152 GHz) and ~1 MW output power.

TE f, GHz U0, kVIb, A

P0, kW(Y=480mm)Diffraction losses, %

17.6 105.011 70 40 1049 3.6118.7 117.506 80 35 1182 2.5620.7 124.048 80 35 1130 1.1821.7 127.315 80 35 1158 1.5722.8 140.046 80 35 1194 1.0223.9 152.442 80 35 1152 1.20

Status of the modified multiStatus of the modified multiStatus of the modified multiStatus of the modified multi----frequency frequency frequency frequency gyrotrongyrotrongyrotrongyrotronwith Brewsterwith Brewsterwith Brewsterwith Brewster----angle window: fabricated; tests in Juneangle window: fabricated; tests in Juneangle window: fabricated; tests in Juneangle window: fabricated; tests in June----July 2007July 2007July 2007July 2007

Double disc output window

Another solution Another solution Another solution Another solution –––– BrewsterBrewsterBrewsterBrewster----angle windowangle windowangle windowangle window

� Full range of second disc movement ±3 mm� Basic gap value ~4 mm� Minimal step of disc movement 2 μm� Accuracy of disc positioning 5 μm� Range of disc angle adjustment ±3 °� Positioning adjustment PC control with feedback

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GyrotronGyrotronGyrotronGyrotron with a circular Brewster window with a circular Brewster window with a circular Brewster window with a circular Brewster window

2006200620062006 ProofProofProofProof----of principle test of a of principle test of a of principle test of a of principle test of a gyrotrongyrotrongyrotrongyrotron with circular with circular with circular with circular Brewster window (0.1 sec, 0.7Brewster window (0.1 sec, 0.7Brewster window (0.1 sec, 0.7Brewster window (0.1 sec, 0.7----0.9MW, 11 modes in 0.9MW, 11 modes in 0.9MW, 11 modes in 0.9MW, 11 modes in the range of 105the range of 105the range of 105the range of 105----143 GHz)143 GHz)143 GHz)143 GHz)

July 2007July 2007July 2007July 2007 ---- 10 sec test of the tube with high10 sec test of the tube with high10 sec test of the tube with high10 sec test of the tube with high----efficient efficient efficient efficient mode converter and Brewstermode converter and Brewstermode converter and Brewstermode converter and Brewster----angle diamond windowangle diamond windowangle diamond windowangle diamond window

BN ceramic, BN ceramic, BN ceramic, BN ceramic, highhighhighhigh----temperature temperature temperature temperature

brazingbrazingbrazingbrazing

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SummaryLast years a significant progress was demonstrated in Russian significant progress was demonstrated in Russian significant progress was demonstrated in Russian significant progress was demonstrated in Russian gyrotrondevelopment for fusion setups:

� Gyrotron efficiency of 50%-60 % has been achieved for several industrial tubes. Efficiency of 70% was shown with the 75GHz/0.8MW/0.1s gyrotron

� 170 GHz/1MW/CW/50% gyrotron for ITER asks for only “cosmetic”development efforts to show the required parameters

� First results of development of multi-frequency and 1.5 MW gyrotron are encouraging

� Two gyrotron test stands are to be brought to operation in 2007 ( 70 kV +30 kV, 100A, 1000 sec at KI, Moscow60kV + 30 kV, 23 A, CW at Nizhny Novgorod)

� Window development (wait for the second paper)

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