1. Collective Thomson Scattering Diagnostics of Confined Fast Ions Paul Woskov 1, S. B. Korsholm 1,2, H. Bindslev 2, J. Egedal 1, F.Leipold 2, F. Meo 2, P. K. Michelsen 2, S. Michelsen 2, S.K.Nielsen 2, E. Westerhof 3, J. W. Oosterbeek 4, J. Hoekzema 4, F. Leuterer 5, D.Wagner 5 1 MIT Plasma Science & Fusion Center 2 Risø National Laboratory, Technical University of Denmark 3 FOM IPP Rijnhuizen 4 IPP, Forschungszentrum Jülich 5 Max Planck IPP ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007

2. CTS Diagnostic Features  CTS diagnostics can diagnose the complete fast ion distribution function, f(v, r, t)  spatially resolved  time resolved  no fundamental limits on energy range  Accessible to plasma core of burning plasmas  Recent experiments in tokamaks have firmly established fast ion CTS  JET (Bindslev et al., PRL 83, 3206, 1999)  TEXTOR (Bindslev et al., PRL 97, 205005, 2006)

3. Principal of CTS Fast Ion Diagnostics Electromagnetic scattering off microscopic fluctuations, principally in electron distribution, driven by ion motion when the condition between fluctuation wavevector (k) and Debye length ( D ) is given by: receiver laser or gyrotron Scattering Geometry In tokamaks Long wavelength sources required for large scat. angles mmwaves for  > 20  Projection of ion velocities v along k diagnosed

4. Tokamak Access for CTS  ECE background restricts access to where the CTS condition (k D ) -1 > 1 can be satisfied  Below fundamental ECE resonance, f i < f B  Used at TFTR and proposed for ITER  Between fundamental and first harmonic, f B < f i < 2 f B  Used at JET, TEXTOR, and ASDEX-Up  Not accessible in burning plasmas with T e > 10 keV  Above the highest significant harmonic, f i > > f B  Used at JT-60 with CO 2 laser for small angle CTS  Used at Alactor C, TCA, and UNITOR for thermal ion CTS with FIR lasers

5. Illustrative CTS Spectrum 110 GHz Gyrotron, 160  Scattering Angle Each ion species and electrons contribute to the total CTS spectrum The fast ions are distinguished in the CTS spectrum by their large Doppler shift above the electron feature (k D ) -1 = 6.7

6. Sensitivity to NBI Ions in ASDEX-Up CTS with 104 GHz Gyrotron, 130  Scattering Angle 100 keV H Beam T e = T i = 6 keV, n e = 8 x 10 19 m -3

7. Sensitivity to ICRH Ions in ASDEX-Up CTS with 104 GHz Gyrotron, 130  Scattering Angle 100 KeV H ion Maxwellian T e = T i = 6 keV, n e = 8 x 10 19 m -3

8. Alphas and Beam Ions in ITER Alpha particles can be distinguished in the presence of 1 MW D beam ions in ITER Egedal, Bindslev, Budny and Woskov, NF, 45, 191 (2005)

9. Alphas and Beam Ions in ITER H-Mode Ion Density Profiles Velocity Space Distribution at Scattering Volume Projected Velocities Along k k Direction

10. CTS Spectrum ITER H-Mode 60 GHz Gyrotron CTS ion signal proportional to ion charge squared

11. Alphas and Beams in ITER Reverse Shear Velocity Space Distribution at Scattering Volume Projected Velocities Along k k Direction Ion Density Profiles

12. CTS Spectrum ITER Reverse Shear 60 GHz Gyrotron

13. Two Fast Ion CTS Systems Implemented  TEXTOR CTS - Operational Gyrotron110 GHz Max. Power200 kW Max. Pulse0.2 sec Rec. Bandwidth106.3-113.4 GHz Channels42 Scat. Angle 150  - 170   ASDEX-Upgrade CTS - Commissioning Gyrotron105 GHz Max. Power800 kW Max. Pulse10 sec Rec. Bandwidth100-115 GHz Channels50 Scat. Angle 84  - 171  Fast ion measurements being carried out in NBI and ICRH plasmas Up to 100 CTS spectra per plasma shot to study ion dynamics makes use of new two frequency gyrotrons First plasma measurements expected in 2007

14. TEXTOR CTS CTS cabinet with DAQ & electronics CTS quasi-optical transmission line CTS port Copper bellow CTS receiver Balcony Liquid N 2 Liner

15. TEXTOR CTS Steerable mirror 1 CC waveguide Receiver Optics inside TEXTOR

16. ASDEX-Upgrade CTS MOU box supporting frames Quasi-optical CTS transmission line Towards the tokamak CTS receiver and electronics cabinet Gyrotron 1 MOU box

17. ASDEX-Upgrade CTS MOU Box #2 Optics CTS Receiver Moveable Mirror Polarizer Plates Exit to CTS Receiver MOU Box #1 MOU Box #2 CTS Receiver CTS Horn From Tokamak

18. TEXTOR CTS Measurements ECE ECE+CTS ICRH co-NBI Frq/GHz CTS Shot # 100477 with ICRH and NBI Gyrotron modulated 2 ms on / 2 ms off Signal from off times (blue) used to determine background (green) to subtract from on times (red) to obtain CTS signal

19. Establishing CTS Beam Overlap Probe CTS receiver Scattering volume Receiver scanned in toroidal direction during Ohmic shot # 100467 Receiver and probe beams go through overlap for a variation of 5  in toroidal angle Corresponds to scat. volume width of 4 cm perpendicular to figure k to B angle 110 

20. Observations of NBI Fast Ion Anisotropy B v cts 45 B v cts 80 Shot # 97982 Shot # 97984 NBI 1 NOTCH FILTER

21. Other Ion CTS Observations at TEXTOR  Sawteeth fast ion dynamics localized in space and orientation, and to lower ion velocities 1  NBI fast ion relaxation after turn off in good agreement with Fokker-plank modeling 1 1 Binslev et al., PRL 97, 205005, 2006  Toroidal rotation of thermal ion population observed

22. Requirements for CTS to Work Understood  Low background electron cyclotron emission (ECE)  Spectrally narrow, clean, and stable probe beam radiation  Sensitive, wideband receiver with deep notch filter for stay light rejection  Receiver robust against gain compression  Well defined, overlapping probe and receiver beams

23. Gyrotron Spectral Adjustments Channel (frequency) Initial Spectrum Channel (frequency) Time (sec) Noise level Probe signal Gain Compression 110 GHz TEXTOR gyrotron adjusted for clean spectrum P(gyro) = 100% 5% 100% Gyrotron Frequency After Tuning 6.5 GHz Careful gyrotron operating parameter adjustment achieves clean spectrum for CTS.

24. Precision Gyrotron Frequency Measurements ASDEX-Up Gyrotron Measurements Modulated Continuous Precision Gyrotron Frequency Measurements Allow: Optimization of receiver notch filters Optimization of receiver blocking switch Improved data analysis Higher frequency resolution measurements Bulk ion feature Plasma rotation Ion Bernstein waves (fuel ratio) Other plasma resonances

25. Gain Compression Without Gain Compression With Gain Compression Red: gyrotron on, Blue: off Compensation Strategies Multiplex IF with narrow central band (TEXTOR 2.56 GHz, ASDEX-UP 1.0 GHz) Use stiff IF amplifiers (Higher output power compression point) Carefully characterize receiver electronics (Eliminate cross talk)

26. Beam Alignment and Mapping Receiver view profile measurements insure well defined view with no side lobes. Locate view position to help facilitate obtaining overlap with gyrotron probe beam Micro-rig

27. Summary  CTS diagnostics can make possible a complete determination of the fast ion distribution function f (v, r, t) in burning plasmas  Experiments at TEXTOR and ASDEX- Upgrade are proving fast ion CTS diagnostics  Practical requirements for making fast ion CTS work in burning plasmas are understood and tractable  A basis for a CTS confined alpha particle diagnostic has been established