1. Present Status of the Nd:YAG Thomson Scattering System Development for Time Evolution Measurement of plasma profile on Heliotron J Takashi Minami, Shohei Arai, Naoki Kenmochi, Hiroaki Yashiro, Chihiro Takahashi, Shinji Kobayashi, Tohru Mizuuchi, Shinsuke Ohshima, Satoshi Yamamoto, Hiroyuki Okada, Kazunobu Nagasaki, Yuji Nakamura, Kiyoshi Hanatani, Shigeru Konoshima, Fumimichi Sano Institute of Advanced Energy, Kyoto University, Gokasho, Uji 611-0011, Japan Takashi Minami, Shohei Arai, Naoki Kenmochi, Hiroaki Yashiro, Chihiro Takahashi, Shinji Kobayashi, Tohru Mizuuchi, Shinsuke Ohshima, Satoshi Yamamoto, Hiroyuki Okada, Kazunobu Nagasaki, Yuji Nakamura, Kiyoshi Hanatani, Shigeru Konoshima, Fumimichi Sano Institute of Advanced Energy, Kyoto University, Gokasho, Uji 611-0011, Japan 2011.11.3 APFA2011

2. Outline Introduction of Heliotron J Recent results SMBI Experiments Plasma startup without ECH Nd:YAG Thomson scattering Introduction Design overview for collective optics polychromator present status of development Summary

3. ITER FFHR HSR SPPS Compact Reactor A steady-state, compact, high-β helical reactor - No disruptions (currentless operation) - No close conducting wall or active feedback control of instabilities (no serious MHD instabilities) - High Q eng (= net P ele. / P oper. ) (at minimum recirculating powers) - High power density (3~4 MW/m 2 under the development of advanced wall materials) Heliotron J Project Aims To Develop Attractive Compact Fusion Reactor

4. Heliotron J Device Major Radius: R=1.2 m Plasma Minor Radius: a=0.1-0.2 m Magnetic Field: B ≦ 1.5 T Vacuum iota: 0.3-0.8 with low magnetic shearHeating System: ECH 0.4MW NBI 0.8MW ICRF 0.4MW Magnetic coil system : one l/m=1/4 continuous helical coil two sets of toroidal coils three pairs of vertical field coils Typical plasma parameters; n e =0.2-4 x 10 19 m -3 T e =0.3-1 keV T i =150-200 eV Inner Vertical Coil Toroidal Coil A Outer Vertical Coil Toroidal Coil B Helical Coil Plasma Vacuum Chamber

5. SMBI Has Extended Operational Regime The stored energy reached Wp~4.5 kJ for ECH(~0.35 MW)+NBI(~0.6 MW), about 50% higher than that of conventional gas-puff fueling. The optimization study of SMBI-relevant operation scenario is in progress. The stored energy reached Wp~4.5 kJ for ECH(~0.35 MW)+NBI(~0.6 MW), about 50% higher than that of conventional gas-puff fueling. The optimization study of SMBI-relevant operation scenario is in progress. Mizuuchi, Contribution to Plasma Physics 50 (2010) 639

6. NBI Plasmas Have Been Successfully Started Up By Assist of 2.45GHz 5kW Microwaves Plasmas of n e =1x10 19 m -3 have been successfully produced 20msec after NBI turn-on with assistance of 2.45GHz 5kW microwaves No high-power ECH is applied Plasma startup without ECH widely will extend the operation region High  experiment B dependence of confinement B dependence of high-energy particles Extension of configuration Off-axis 70GHz ECH Kobayashi, Nucl. Fusion 51 (2011) 062002

7. Production of Low-Density Plasma and High-Energy Electrons by 2.45GHz Microwaves is Important No density build-up There is no EC resonance for 2.45GHz microwaves Plasma is successfully started up when ECE intensity exceeds a critical value

8. Objective for Construction new Nd:YAGThomson Previous experiments show the improved confinements phenomena accompany with the transient phenomena. The plasma profile is rapidly changed by the transition. Therefore, the time evolution of the plasma profile should be measured to understand the physics of the improved confinement. For this purpose, we are developing new Nd:YAG Thomson scattering system for Heliotron J device.

9. Design of Heliotron J Nd:YAG Thomson system Goal: Performance Spatial resolution ~1cm Spatial channels : 25 Time intervals of measurement ~10ms (Period of discharge ~200ms,confinement time~1-10ms) Range of T e 10eV-10keV Range of n e >0.5x10 19 m -3 Nd:YAG Laser spec 100Hz (50Hz two lasers), 550mJ 10ns pulse by Continuum.inc. We have a future plan to improve time interval to ~5ms (2 lasers->4 lasers) Goal: Performance Spatial resolution ~1cm Spatial channels : 25 Time intervals of measurement ~10ms (Period of discharge ~200ms,confinement time~1-10ms) Range of T e 10eV-10keV Range of n e >0.5x10 19 m -3 Nd:YAG Laser spec 100Hz (50Hz two lasers), 550mJ 10ns pulse by Continuum.inc. We have a future plan to improve time interval to ~5ms (2 lasers->4 lasers)

10. Schematic of YAG Thomson Scattering system

11. Design of Scattered Light Collective System Dimeter: 800mm F/2.25 20 度 (mm) Scatter volumeimage concave mirror Scattered angle:20deg. 25 spatial points ->resolution ~10mm Image length:14cm Scattered angle: 20degree Laser Length inside plasma: 25-30cm Magnification: 0.3-0.5 Large concave mirror is used for large solid angle Higher F number for low aberration

12. Solid angle and aberration ✓ Large solid angle: 0.08-0.1str. =>Considerable scattered light can be collected ✓ Back scattered light is small due to small backward region. =>Good S/N ratio ✓ Aberration (<3mm) is small due to larger F number (Fiber width ~3mm) ✓ It is easy to choose optical fiber, because required fiber NA(numerical aperture) is >0.25. ✓ Uniform optical characteristic for all spatial points ✓ Large solid angle: 0.08-0.1str. =>Considerable scattered light can be collected ✓ Back scattered light is small due to small backward region. =>Good S/N ratio ✓ Aberration (<3mm) is small due to larger F number (Fiber width ~3mm) ✓ It is easy to choose optical fiber, because required fiber NA(numerical aperture) is >0.25. ✓ Uniform optical characteristic for all spatial points >80mstr <3mm ~0.25

13. 6 channel Interference Polychromator Polychromator Wavelength channel 5ch. Rayleigh channel 1ch. Interference filter Relay lens Detector Avalanche photo diode -Hamamatsu photonics: S8890- 30,[area: 3Φ] Bias: High voltage regulator with temperature control Preamplifier is made by JFET input OP amplifier. APD HV regulator

14. Amplifier performance Signal response by SPICE Circuit Simulator ADA4817 Output signal of preamplifier Gate width 60ns-80ns APD signal Time manufacturer C in (F) G.B.(MH z) S.R. (V/μs) I out (mA) e n (nV/√Hz) ADA4817 Analog Devices 1.5p410870704n OPA627 Texas Instruments 8p1655454.5n LF356 National Semiconductor 3p512512n

15. Design for Filter Combination of Polychromator Filter Combination Ch1(FIlter1) : 700-845nm Ch2(FIlter2) : 845-960nm Ch3(FIlter3) : 960-1025nm Ch4(FIlter4) : 1025-1050nm Ch5(FIlter5) : 1050-1060nm Filter Combination Ch1(FIlter1) : 700-845nm Ch2(FIlter2) : 845-960nm Ch3(FIlter3) : 960-1025nm Ch4(FIlter4) : 1025-1050nm Ch5(FIlter5) : 1050-1060nm T e : 10-10keV n e : 3x10 19 m -3 Error is below 2% for T e and 3% for n e 制動輻射だけを考慮 T e : 10-10keV n e : 3x10 19 m -3 Error is below 2% for T e and 3% for n e 制動輻射だけを考慮 Filter Combination Ch1(FIlter1) : 700-845nm Ch2(FIlter2) : 845-960nm Ch3(FIlter3) : 960-1025nm Ch4(FIlter4) : 1025-1050nm Ch5(FIlter5) : 1050-1060nm Filter Combination Ch1(FIlter1) : 700-845nm Ch2(FIlter2) : 845-960nm Ch3(FIlter3) : 960-1025nm Ch4(FIlter4) : 1025-1050nm Ch5(FIlter5) : 1050-1060nm T e : 10-10keV n e : 3x10 19 m -3 Error is below 2% for T e and 3% for n e 制動輻射だけを考慮 T e : 10-10keV n e : 3x10 19 m -3 Error is below 2% for T e and 3% for n e 制動輻射だけを考慮 T e : 10-10keV n e : 3x10 19 m -3 Error from bremsstrahlung is below 2% for T e and 3% for n e Filter set optimization using modeling code. T e : 10-10keV n e : 3x10 19 m -3 Error from bremsstrahlung is below 2% for T e and 3% for n e Filter set optimization using modeling code. >80%

16. Development of Data Acquisition System for Fast SIgnal Polychromators25x6ch.=150ch.Polychromators25x6ch.=150ch. V792 QDC 32ch.x5 32ch.x5CINOSControllerMemoryVMECAMACCINOSControllerMemoryVMECAMAC Heliotron J FedoraLinux Data base Heliotron J FedoraLinux Data base CAEN V792 32 Channel Multi-event QDC （ Charge-to-Digital Conversion) VME bus system based on CHS CINOS system V792 CINOS

17. Movie:Manufacturing new port on Heliotron J Outer Port Inner Port

18. New Heliotron J port for Nd:YAG Thomson Window for scattered light(30cm) Laser injection port Heliotron J

19. New Nd:YAG Thomson Scattering Stage

20. Summary To investigate the relation between the plasma profile and the improved confinement on Heliotron J. We develop the new Nd:YAG Thomson scattering system. Spatial resolution ~1cm Spatial channels : 25 Time interval of measurement ~10ms Range of T e 10eV-10keV Range of n e >0.5x10 19 m -3 Laser optics, Collection optics for scattered light (Concave mirror, optical fiber bundles), Polychromator (filter combination, relay lens, preamplifier), Data acquisition system are developed. To investigate the relation between the plasma profile and the improved confinement on Heliotron J. We develop the new Nd:YAG Thomson scattering system. Spatial resolution ~1cm Spatial channels : 25 Time interval of measurement ~10ms Range of T e 10eV-10keV Range of n e >0.5x10 19 m -3 Laser optics, Collection optics for scattered light (Concave mirror, optical fiber bundles), Polychromator (filter combination, relay lens, preamplifier), Data acquisition system are developed.