Shin KUBO, Masaki NISHIURA, Kenji TANAKA, Takashi SHIMOZUMA, Yasuo YOSHIMURA, Hiroe IGAMI, Hiromi TAKAHASHI, Takashi MUTOH National Institute for Fusion Science Collective Thomson Scattering Study using Gyrotron in LHD Research Center for Development of FIR Region, Univ. of Fukui Yoshinori TATEMATSU, Teruo SAITO Namiko TAMURA, Dept. Energy Science & Technology, Nagoya Univ. US-Japan Workshop on RF Physics 2010.03.8-10 General Atomics, San Diego
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Collective Thomson Scattering Study using … f0+df f0+df+fs gyrotron df~200MHz power monitor ECRH Transmission line (corrugated waveguide) fixed local oscillator stability < 10 MHz
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Hiromi TAKAHASHI, Takashi MUTOHNational Institute for Fusion Science
Collective Thomson Scattering Study using Gyrotron in LHD
Research Center for Development of FIR Region, Univ. of FukuiYoshinori TATEMATSU, Teruo SAITO
Namiko TAMURA,Dept. Energy Science & Technology, Nagoya Univ.
US-Japan Workshop on RF Physics2010.03.8-10 General Atomics, San Diego
Contents
•ECRH System in LHD --> Potential as a diagnostic tool•Collective Thomson Scattering•Receiver•Preliminary results•Scattering Volume and CTS spectrum•Sub-Tera Hz Gyrotron Development•Future Plan•Summary
ECRH System
Design of the Antenna System of ECRH in LHD
• Two sets of upper antennas from 5.5U and 9.5 U port for 82.7GHz and 168GHz
• Two 84 GHz Antenna from 1.5 L port
• All antennas can focus and deposit the power within r<0.2 for Rax=3.53m,B=2.951 T
• Antenna Scan Range– U antenna
• R=-3.2-3.8m, t=±0.2m on mid plane
– L antenna• R=-3.0-4.2m,t= ±1.5m
6
Elliptical Gaussian Beam Focusing Scheme
168GHz Beam
SteeringMirror
FocusingMirror
from Waveguides
84GHz Beam
SteeringMirror
FocusingMirror
mid-plane Focusing MirrorBi-focal Mirror
Waveguide mouth
Hot test of beam steering/focusing• Errors of steering for tor/rad-directions notably affect deposition profile• Beam steering/focusing were checked in vacuum vessel of LHD by using
Kapton film and IR-camera.
ECRH Beam as a Scattering Probe Beam• Well defined beam for heating is also suitable
for probe beam for scattering measurement.– High power density, High Frequency
Γ: geometrical factorre: classical electron radiusne: electron densitydω: band widthrR: beam radiusλs0: wavelength of scattered
radiationS(k,ω): scattering form factor
Probebeam
Scatteredbeam
fromGyrotron
toReceiver
SN ratio of CTS
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Scattered Power
U-antenna for 168 GHz used for 77 GHz Scattering
•Beam evolution is recalculated with the 168 GHz antenna mirror configuration radiated from the same waveguide mouth for 77 GHz beam •Resultant beam sizes on the mid-plane are •20 mm in radial •99 mm in toroidal
If the configuration of the mirrors and optical axis are the same,i. e. cosφ and ρ are kept ,relation between Rin and Rout are defined by
even for different frequency, or beam size
77 GHz168 GHz
bi-focal mirrorfinal focus mirror
7777
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Scattering using Gaussian Beam
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Cross Volume of Gaussian Beam
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Surface of Cross Volume
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Cross Volume and resolution
49
Scattering using Gaussian Beam
Scattering Length
50
Scattered intensity and effective scattering length well scale
center
top
bottom
Scattered spectrum are fitted with offset-Gaussian to subtract ECE background
Intensity ratio of the scattered power well scales to the calculated effective scattering length
Comparison of Exp. / Cal. Spectrum
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Measured data are used for calculation.• Te=0.6keV• TAr=0.7keV• ne=2.5x1019m-3
• nfast=0.1x1019m-3
• Ti=0.7keV is better fitting than Ti=2keV.
• Measured data seems to have an offset of +0.1GHz.
• P(3.6,0,0), R(3.6,0,0)• Vsc=153.3cm3
1
10
100
1000
-3 -2 -1 0 1 2 3
Calculated CTS spectrumscattered radiation
Scat
tere
d Po
wer
(eV)
frequency (GHz)
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Sub-Tera Hz Gyrotron
Development
FIR FUCTS in LHD
fi > 4fce suppression of ECE400 GHz band is one choice. Salpeter Parameter
Linked with slide 15
R along scattered wave path (m)
FIR FU
Achieved 50 kW
• More than 50 kW at 349 GHz and about 40 kW at 390 GHz have been achieved. These are highest powers as second harmonic oscillation of gyrotron.
• Oscillation efficiency decreases for large beam current possibly due to degradation of the quality of the electron beam.
• CTS spectrum and reduction of ion/fast ion temperature
• Calibration including polarizer/waveguide coupling
• Multi receiver / fast volume scan• Precise background subtraction
• Simultaneous measurement in 2-D velocity space
• Expansion in real/velocity space
• Sub-Tera Hz Gyrotron Application to CTS
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LHD ECH Antenna used for probe and receiving beams
3
9.5U Antennaout 82.7 GHzin 77 GHz
5.5U Antennaout 77 GHzin 168 GHz
1.5L Antennaout 84 GHzin 84 GHz
2-O Antennaright 77 GHzleft 168 GHz
3.5 inch corrugated WG
3.5 inch corrugated WG
3.5 inchcorrugated WG
1.25 inch corrugatedWG
waist size 0.03 m 0.8 MW/5s, 0.24 MW/CW
ECRH Horizontal Antennafor parallel component
• 2 sets of• Focusing Mirror
• Symmetric Gaussian Beam
• 35 mm waist size at plasma center
• Steering Plane Mirror• Toroidally +/- 30
degree• Poloidally +/- 10
degree
Summary•Started CTS utilizing ECRH system in LHD77GHz ( P~1MW) Gaussian beam is used as a probe.Injection ECRH antenna is used as a receiver. Backward, perpendicular 8/32 channel receiver system is attached to ECRH transmission line 3 s, 50 Hz modulated injection at 0.7 MWPreliminary results with 8/32 channel show promising CTS signals
•32 channel•Higher reliability in ion velocity distribution reduction
•Examining possible use of horizontal antennas•Backward, parallel components