T. Biewer, March 3 rd, 2003NSTX Physics Meeting Measurements of Edge Impurity Ion Dynamics During RF Heating T. M. Biewer, R.E. Bell March 3 rd, 2003 NSTX Physics Meeting Princeton Plasma Physics Laboratory

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Outline Overview of the Edge Rotation Diagnostic Observations during NB plasmas Observations during RF plasmas Summary

T. Biewer, March 3 rd, 2003NSTX Physics Meeting ERD Sightlines Poloidal Chords Poloidal View Toroidal View Poloidal and Toroidal views are imaged through a single spectrometer onto a single detector. Neutral Beam Trajectories RF antenna

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Sample Shot : NB heated, long H-mode From Dave Gates’ rtEFIT development XP on Feb. 10 th, 2003 Three source, NB heated, D 2 plasma Long H-mode period from ~240 ms to ~460 ms CHERS/ERD data integrated every 10 ms until 500 ms  50 frames of ERD data over the discharge

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Sample Shot : raw ERD data t= s ~wavelength Poloidal views Toroidal views Edge most Core most Fiber The CCD is binned from 512x512 pixels to 512x47 in order to decrease the read-out time. Each time frame of the CCD contains:  6 poloidal views  7 toroidal views  10 ms of integrated, dispersed light  X-axis: ~wavelength  Y-axis: ~ radial location Each fiber is spread over multiple pixels to avoid saturation  Color indicates light intensity

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Sample Shot : a sample spectrum ~4595 Å ~4705 Å The high dispersion, axial transmission grating used in the Kaiser-Spectrometer allows for very high throughput of light and fine spectral resolution. ~22 photons/count from CCD This data taken at f/11 (accepts f/1.8) 97.3% of light thrown away to avoid detector saturation

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Impurity Ion Dynamics from C III, C IV, and He II C III triplet eV ionization 3S to 3P0 transition relatives amplitudes from theory Can fit all 3 lines simultaneously to get very accurate v, T He II eV ionization C IV doublet eV ionization 2G to 2F0 The ERD relies on the intersection of the sightline with the intrinsic emission shell for localization. But each sightline measures aspects of different emission shells, which peak at different radii.

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III Dynamics During Shot H-mode End of I p ramp NB addition H-mode transition ELM-free period Key No change in v,T with additional NB power More negative velocity at H-mode transition Increase in T i during ELM-free period

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III Profile Dynamics During Shot Signal Brightness EFIT LCFS (red line) is in good agreement with ERD C III shell location. ELM-free periods H-mode Temperature Tor. And pol. Views show a minimum in Ti at the LCFS? Velocity ELM-free H-mode reduces the measured velocity

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III Profile Dynamics During Shot Signal Brightness EFIT LCFS (red line) is in good agreement with ERD C III shell location. ELM-free periods H-mode Temperature Tor. And pol. Views show a minimum in Ti at the LCFS? Velocity ELM-free H-mode reduces the measured velocity

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III Profile Dynamics During Shot Signal Brightness EFIT LCFS (red line) is in good agreement with ERD C III shell location. ELM-free periods H-mode Temperature Tor. and pol. Views show a minimum in Ti at the LCFS Velocity ELM-free H-mode reduces the measured velocity

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Profiles Before and After H-mode Transition Signal Brightness Outward shift and narrowing in the peak brightness during H- mode consistent with generally hotter edge and steeper T e gradient Temperature tor. and pol. Views show a minimum in Ti near the LCFS Velocity ELM-free H-mode reduces the measured velocity Toroidal ViewPoloidal View

T. Biewer, March 3 rd, 2003NSTX Physics Meeting E r ~-v x B suggest improved e - confinement Before H-mode transition After H-mode transition

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Sample Shot : RF Heating, He plasma Poloidal View Toroidal View Poloidal views Toroidal views From Phil Ryan’s HHFW CD XP-312 on Feb. 12 th, 2003 He plasma 4.3 MW of RF 30 MHz

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Sample Shot : RF Heating, He plasma Poloidal View Toroidal View Poloidal views Toroidal views

T. Biewer, March 3 rd, 2003NSTX Physics Meeting He II spectra during Shot RF on RF off Two successive time frames clearly show the spectral consequences of RF heating in the edge plasma. Poloidal, r tan ~146 cm Pixel # counts

T. Biewer, March 3 rd, 2003NSTX Physics Meeting A single Gaussian fit of He II does not capture the dynamics. Poloidal, r tan ~146 cm Pixel # counts data 1G fit: T i =387 eV v=-40 km/s data-1G fit

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Two thermal populations of He II ions are present during RF. Poloidal, r tan ~146 cm Pixel # counts data 2G fit: T i =490 eV, 40 eV v=-50 km/s, -10 km/s data-2G fit On the same order as NB heated plasmas High temp. pop. excited by RF Fitting the data with two Gaussians gives a much better representation of the data.

T. Biewer, March 3 rd, 2003NSTX Physics Meeting He II Dynamcis During Shot : Poloidal He II ion. pot. 54 eV 1G fit 2G high 2G low Key r tan ~146 cm ~300 ms to estab. pop. ~30 ms to remove pop.

T. Biewer, March 3 rd, 2003NSTX Physics Meeting He II Dynamcis During Shot : Toroidal He II ion. pot. 54 eV 1G fit 2G high 2G low Key r tan ~146 cm

T. Biewer, March 3 rd, 2003NSTX Physics Meeting He II Low v. High populations (Pol.)

T. Biewer, March 3 rd, 2003NSTX Physics Meeting He II Low v. High populations (Tor.)

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Single Gaussian C III T i increases with P RF Poloidal, r tan ~146 cm Each color is a different shot [ ] (co-CD), multiple time points are plotted for each shot C III ionization potential (47 eV) NB heated plasma equivalent T i (~30 eV) TS int. T e (r=146 cm)

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Single Gaussian C III T i increases with P RF Toroidal, r tan ~146 cm Each color is a different shot [ ] (co-CD), multiple time points are plotted for each shot C III ionization potential (47 eV) NB heated plasma equivalent T i (~30 eV) TS int. T e (r=146 cm)

T. Biewer, March 3 rd, 2003NSTX Physics Meeting On-axis T e also increases with P RF

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III (SG) velocity

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Summary New measurements from the ERD are emerging –Dynamics of C III, He II, and C IV NB heated plasmas –C III shell is inside the LCFS (EFIT) –Apparent minimum in T i at LCFS –No large edge v or T i changes as NB power increases –ELM-free H-mode corresponds with larger v x B RF heated plasmas –RF influence seems to favor two populations of He II ions in the edge –Anisotropy in toroidal v. poloidal view may indicate anisotropy in parallel v. perp. dist. func. –~300 ms are needed to establish the “hot” component of the dist. Func, but it is lost in ~30 ms or less –“perp.” temperature grows like sq.root P RF Much future work remains

T. Biewer, March 3 rd, 2003NSTX Physics Meeting C III Impurity Dynamics During Shot

T. Biewer, March 3 rd, 2003NSTX Physics Meeting

T. Biewer, March 3 rd, 2003NSTX Physics Meeting

T. Biewer, March 3 rd, 2003NSTX Physics Meeting Some Geometric Considerations Pitch angle of B at the midplane is ~28.5° (EFIT) Each view is sensitive to parallel and perpendicular velocity distributions – sin  p =.477 cos  p =.879 tan  p =.543 Pol. View sees ~75% perp. Dist., ~25% parl. Tor. View sees ~75% parl. Dist., ~25% perp. Speculation: RF excites the perp. Dist. Function: –f c,He =qB/2  m=1.14 MHz, the 27 th harmonic of 30 MHz –r L =v perp,therm /  c =mv perp,therm /qB=1.53 cm

T. Biewer, March 3 rd, 2003NSTX Physics Meeting ERD sightlines in detail Poloidal Chords Toroidal Chords 10 ms time resolution. 6 toroidal and 7 poloidal rotation chords covering 140 to 155 cm. Local E r =v  B-  p/eZn Does not require neutral beam. Sensitive to C III (near separatrix) and C IV (inside, but weaker). Cold plasma broadens C III emission shell, resulting in possible  E r measurement. Edge rotation measurement complements main- CHERS. Poloidal Chords

T. Biewer, March 3 rd, 2003NSTX Physics Meeting