1. Tangential multi-color “optical” soft X-ray array for fast electron temperature and transport measurements L. F. Delgado-Aparicio, D. Stutman, K. Tritz, and M. Finkenthal The Plasma Spectroscopy Group The Johns Hopkins University R. Bell, D. Johnson, R. Kaita, B. LeBlanc and L. Roquemore Princeton Plasma Physics Laboratory Princeton Plasma Physics Laboratory NSTX Results/Research Forum December, 12-17, 2005 Princeton, New Jersey, USA

2. Principles of the “optical” soft x-ray (OSXR) array Conversion to visible light OSXR array head tested on CDX-U & NSTX spherical tokamaks (2004) It’s a system that uses a fast (  1  s) and efficient scintillator (CsI:Tl) in order to convert soft x-ray photons (0.1<E ph <10 keV) to visible green light (  550 nm). To discrete channels and light (PMT and/or APDs) amplifiers vacuum

3. Motivation Fast (  100  s) T e measurements. (ECE-like diagnostic for STs and Tokamaks)  Perturbative electron heat and particle transport ( ELMs, pellets, gas-puff and/or SGI ).  MHD related T e perturbations ( ELMs, MHD-modes, RWMs, FISHBONES/EPMs ). Perturbative impurity transport. (Gas puff (Ne), Impurity pellets (C, B) and/or SGI) Our previous work with the USXR and the 1-color OSXR systems have shown that the measurements proposed are feasible. Explore the possibilities of the proposed diagnostic in poloidal configuration.  Viewing the same plasma volumes at three energy ranges.  Higher SNR in comparison to diode-based arrays.

4. How to design a diagnostic to measure T e (r,t)? Tangential multi-color (3) optical soft x-ray (tMC-OSXR) array Multi-color technique (two-foil method): The T e measurement is obtained by rationing the localized radiation intensities from two energy ranges, rather than from an absolute intensity measurement, as is in the case of a single color instrument. This design approach naturally eliminates a number of factors that degrade the accuracy of the conventional single color SXR diagnostics for T e measurements.  Absolute value of the T e (r) by minimization techniques!  Feedback n e (r,t)  n Z (r,t)

5. NSTX tangential “optical” soft x-ray (tOSXR) array Rtg 00 ~146.5 cm Rtg 15 ~84 cm FOC 8” CF flange with FOW Soller slits 8” CF flange Filter holders (10, 100 and 300  m) 4” 8” Baffles 2 cm Details of the optical head Filter holder Baffles 2 cm Components 1.Baffles + filters 2.Soller slits 3.Scintilator + FOW 4.Fiber optics 5.PMTs + shield 6.Amps 7.DAQs

6. NSTX shot # 117951 What happen with S n & T e for t  [0.2,0.35] ? 150 ms SNR 10 um ~ 247 SNR 100 um ~558 SNR 300 um ~ 953 IpIp NBI RF SnSn SnSn DD T e0 from tangential line-integrated multi-color ratio Time history of soft X-ray signals SNR 100/10 ~ 171 SNR 300/10 ~ 196 (RS L-mode)

7. t1t1 t2t2  60 eV t1t1 1.6 1.54 T e (r,t) and neutron rates (S n ) crashes keV  130 eV t2t2 1.97 1.84 “First cut” T e (r,t) tOSXR space-time profile 1.3 2.2 keV “First cut” T e (r,t) tOSXR space-time profile 1.3 2.2 keV

8. 1 2  60 eV 1.6 1.54 5 ms Fishbone  130 eV 1.97 1.84 5 ms Fishbone T e (r) drops: what is preventing the T e0 from peaking?

9. MHD fishbones affect background plasma during  fish <  sd [1] M. F. F. Nave, et al., Fishbone activity in JET, NF, 31, 697, (1991). [2] T. Kass, et al., The Fishbone instability in ASDEX Upgrade, NF, 38, 807, (1998). [3] S. Günter, et al., The influence of Fishbones in the background plasma, NF, 39, 1535, (1999). n=1 Fishbones (5 kHz < f < 30 kHz) 1.3 2.2 keV Observations 1.Each fishbone burst affect the T e distribution (  T e <0) only during the phase of largest amplitude of the MHD oscillation, that is ~ 2-3 ms (  fish <  sd ). 2.The magnitude of the central  T e0 is generally correlated with the amplitude of the individual fishbone. 3.The USXR array identifies fishbones as a reconnection- sawtooth-like processeses (but in a slower time-scale in accordance with tOSXR array). 4.Fishbones can also affect impurity density profiles, avoiding their central peaking. 5.  n e measured by UCLA reflectometer 6.  q 0 after the fishbones have disappeared  q 0 ~0.4  q 0 ~0.7  Fishbones in NSTX can lead to a redistribution of T e and n Z similar in form to a sawteeth, but with the plasma parameter variation occurring on a significantly longer time- scale (  fish <  sd ). 2-4 ms

10. DD NSTX shot # 117903 Normalized contour plots of tangentially- line-integrated soft x-ray signals, filtered with Be foils with thicknesses of 10, 100 and 300  m, respectively. Shown here is the effect on the soft x-ray intensity of an edge-localized-mode (ELM) occurring at  327 ms 5 ms 1 0.5 0 t1t1 t2t2 t1t1 Type I ELMs study (see also K. Tritz presentation)

11. Type I ELM T e (r,t) profiles:  t 1 NSTX shot # 117903, t  [0.3,0.35] 5 ms 50 eV 850 eV edge core inboard ELM

12. Type I ELM SXR and T e (r,t) profiles:  t 2 50 eV 1050 eV NSTX shot # 117903, t  [0.35,0.4] (Be10/Be300) 6 ms edge core inboard

13. Future: re-entrant “multi-color” OSXR system? OSXR array head tested on NSTX NSTX (07) & NCSX It’s a system based on the OSXR concept with an optimized plasma access and the capability of recording MHD phenomena from the core to the periphery SIMULTANEOUSLY!

14. Further work Perform the Abel inversions! Modify the filter holder to enable photometric calibration in absence of foils. Use 500  m Be foil for increase contrast. Use transimpedance amplifiers (bandwidth: DC-50 kHz) module behind PMT. Rotate the tOSXR for better plasma access. Conclusions 1.We have designed, build, installed and tested the prototype version of a tangential multi-color optical SXR array for fast electron temperature measurements. 2.Line integrated signals enabled the measurement of fast electron temperature profiles in good agreement with the (slow) Thomson Scattering measurements. 3.The tosxr array can work in a variety of plasma scenarios (L-mode & H- mode). 4.However in the cases of strong inhomogeneities in the local plasma characteristics the limitation of the use of line integrated signals become apparent.

15. Acknowledgments The Johns Hopkins University: Gaib Morris, Scott Spangler, Steve Patterson, Russ Pelton and Joe Ondorff. Princeton Plasma Physics Laboratory: Mike Bell, Bill Blanchard, Thomas Czeizinger, John Desandro, Russ Feder, Jerry Gething, Scott Gifford, James Kukon, Doug Labrie, Steve Langish, Jim Taylor, Sylvester Vinson, Doug Voorhes and Joe Winston (NSTX). This work was supported by The Department of Energy (DOE) grant No. DE-FG02-86ER52314ATDOE