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27 th EPS Conference on Controlled Fusion and Plasma Physics BUDAPEST, HUNGARY, 12-16 JUNE 2000

ASIPP. HT-7. 27 th EPS Conference on Controlled Fusion and Plasma Physics BUDAPEST, HUNGARY, 12-16 JUNE 2000 . MULTIPOINT ND THOMSON SCATTERING ON HT-7. J. Mao, J.Zhao, Y.D.Li, A. Xie, Z. Fang, V.Sannikov* A. Gorshkov* Institute of plasma Physics, Academia Sinica,

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27 th EPS Conference on Controlled Fusion and Plasma Physics BUDAPEST, HUNGARY, 12-16 JUNE 2000

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  1. ASIPP HT-7 27 th EPS Conference on ControlledFusion and Plasma PhysicsBUDAPEST, HUNGARY, 12-16 JUNE 2000 MULTIPOINT ND THOMSON SCATTERING ON HT-7 • J. Mao, J.Zhao, Y.D.Li, A. Xie, Z. Fang, • V.Sannikov* A. Gorshkov* • Institute of plasma Physics, Academia Sinica, • Hefei, Anhui, 230031, P.R.China. • * PRC Kurchatov Institute, Moscow 123182. RUSSIA

  2. ASIPP HT-7 ABSTRACT • A compact, low cost, multipoint Thomson scattering diagnostic for HT-7 Superconducting Tokamak has been in operation. Its capability of measuring electron temperatures is 200ev to 2kev at densities of a few times 1012 cm-3, a spatial resolution of 2.4cm for 5 spatial points and a temporal resolution of 1ms-1s for 8 time points. The major components consist of 20-25J Nd:glass laser with 35ns width (8 pulses per burst), KDPdoubling unit; Spherical mirrors of multipass input optical system; wide-angle collection objective, bandpass glass filter for reducing the stray light to zero; f/2.5 polychromator, the fiberglass collimator, the photomultiplier’s box with electronic preamplifier, high gain and high signal/ noise ratio, CAMAC data acquisition and so on. The multipass optical system has been successful for increasing the quantity of scattered photons by laser beam passes 10 times through plasma. The HT-7 Thomson scattering diagnostic has provided successfully the information on two dimensional electron temperature in the plasma of HT-7 tokamak with LHCD and IBW heating.

  3. CAMAC 2250 PMT HT-7 ASIPP HT-7 FIBER BAND FILTER PLCRO. CALIB KDP KDP filter PRISM FILTER AMPLIFIER OSILLATOR POWER SUPPLY Layouts of HT-7 T.S.

  4. ASIPP HT-7 PARAMETERS of HT-7 T.S. Te~0.2-2keV; Nelim > 2  1012 cm-3 Spatial resolution : 2.4cm for 5 spatial points (0, 4cm,8cm,12cm,16cm) Temporal resolution : 1ms-1s for 8 points Nd Laser: Nd:glass laser, 20-25J1.06,4J0.53 (KDP doubling),width 35ns 1 or8 pulses.

  5. spherical mirrors Filter spherical mirrors lens Laser Prism PMT FIBER COLLECTOR

  6. ASIPP HT-7 COMPONENT Nd Laser Optical system Polychromator and PMT Fibelglass collimator Data Acquisition,CAMAC Filter and Multipass Calibration System

  7. ASIPP HT-7 Nd:glass Laser System Oscillator ; an Amplifier; KDP crystal; Energy meter;Glass filter to cut off light of 1.06 Laser room

  8. ASIPP HT-7 OSCILLATOR * Ring resonator very stable * LiF crystal with colored,Qswitch * 50mJ, 40 nsec., line width<0.01Å Operate in a TEMoo *Two opration model. 1Hz repetition1 or 8 pulses * Dove prism with Brester’s angles.Light beam is rotated inside the resonator along the optical axis reduce the thermal stress which are accumulated during the operation

  9. ASIPP HT-7 AMPLIFIER * Telescopic resonator 7 passes * LiF-2 plate with cororedfor Q switch,width 35ns for protecting the master oscillator from back-emission * Increasing laser power density by KDP’s nonlinear process.

  10. PMT OBJECTIVE FIBER COLLECTOR GRATING ASIPP HT-7 POLYCHROMATOR * Transmission about 0.7-0.8 * Diffraction grating 600 L/mm, 1515cm2 * Wide-angle collection objective (F=200mm) * f=1/2.5

  11. ASIPP HT-7 S20 PHOTODETECTORS * 25 Pieces ( 5 x 5 ) * S-20 PHOTOCATHODE * Quantum Efficiency (5300Å ) , 10%-12% (6943Å~3%) * 12 Dynodes Dnode dark Current ~ 10-8 * High Gain * Preamplifiers: 50times, Bandpass: 0.15-35MHz

  12. ASIPP HT-7 BANDPASS GLASS FILTER * Two pieces installed frond of the input fiberglass guides * Reduce the stray light to zero * Special glass filter used cut off of laser radiation(1.06μ) * High damage resistant for high power laser

  13. ASIPP HT-7 spherical mirrors Filter spherical mirrors lens Laser Prism MULTIPASS OPTICAL   E=E0(1+R+R2+R3+....R9)==9.8EO  Two spherical mirrors R>>D 2R=3.2m, D=0.052m * Two pieces installed frond of the input fiberglass guides Reduce the stray light to zero  Success for Lager Device firstly

  14. ASIPP HT-7 Tungsten Lamp To CAMAC chopper lens lens Photodiode fiber CALIBRATION SYSTEM  Optical Path Alignment (HeNe and Laser)  Energy Calib. (Energy Meter)  Spectral Calib. (Hg lamp)  Spatial position Calib. (movable target)  Sensitivity of 25 Channel (Tungsten Lamp)

  15. ASIPP HT-7 FLOW CHART OF THOMSON SCATTERING SYSTEM

  16. ASIPP HT-7 Profile of Te(r)

  17. ASIPP HT-7 High Te0 ~ 1KeV during LHCD Te by T.S compare with Te by ECE

  18. ASIPP HT-7 Profile of Te(r) IBW250kw LHCD420kw

  19. ASIPP HT-7 600ms 600ms 33055 33055 450ms 33051 Ip=130KA, Ne~1.51013/cm3with IBW 150kw Te by SXS Te by T.S.

  20. ASIPP HT-7 SUMMARY • The multipass optical system has been successful for increasing the quantity of scattered photons. • The HT-7 Thomson scattering diagnostic has provided successfully the information on two dimensional electron temperature and density profiles in the plasma of HT-7 tokamak with LHCD and IBW heating.

  21. ASIPP HT-7 SUMMARY • The multipoint Thomson scattering diagnostic for HT-7 Tokamak has been in operation. • Nd Laser: Nd:glass laser, 20-25J1.06,4J0.53; 1or 8 pulses. Optical system is very stable. • System stray light was reduced to near zero by Two pieces of glass filter. • The ratio of noise to signal is < 5%.

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