1 / 8

EBW Emission & Coupling Physics Important for T e (R) Diagnostic Development & EBWCD System Design

chase-lee
Download Presentation

EBW Emission & Coupling Physics Important for T e (R) Diagnostic Development & EBWCD System Design

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. XP514: Thermal Electron Bernstein Wave Emission & Coupling on NSTXG. Taylor1, J.B. Caughman2, S.J. Diem1, P.C. Efthimion1, B.P. LeBlanc1, R.W. Harvey3,J. Preinhaelter4, J.B. Wilgen21)Princeton Plasma Physics Laboratory2) Oak Ridge National Laboratory3) CompX4) Czech Institute of Plasma PhysicsNSTX Results ReviewDecember 13, 2005

  2. EBW Emission & Coupling Physics Important forTe(R) Diagnostic Development & EBWCD System Design • Need resilient EBW coupling for EBWCD & Te(R) diagnostic • XP514 studied oblique O-mode 2nd harmonic EBW coupling AORSA-1D NSTX  = 40% Bt(0) = 3.5 kG f = 28 GHz M. Carter ORNL Where: Y = ce/

  3. Dual-Channel 20-40 GHz Radiometer & Quad-Ridged Horn Provides Orthogonal Polarization Measurements • Measure Te(R,t) via thermal EBW emission • Analyze polarization of thermal EBW emission • Demonstrate > 80% coupling of thermal EBWs at ~ 28 GHz • Antenna could be manually steered with some difficulty Experiment Goals:

  4. Obtained Good EBW Emission, Te, ne & EFIT Data to Compare to Modeling, Despite Locked Modes • NBI-heated H-mode target plasma; measured EBW emission between 24 & 32 GHz during dedicated half-day • Acquired data at Ip = 0.8 & 0.9 MA, early termination at Ip = 1 MA due to locked mode • Ran frequency scan at Ip = 0.8 MA, but conditioning/fueling changed & developed locked modes during scan • Emission bursting events, particularly immediately prior to locked modes • Compared experimental results to full wave mode conversion & 3-D ray tracing codes

  5. Evolution of Measured 24-32 GHz EBW Emission from H-Mode had Trad ~ 2-4 Times Smaller than Simulation Simulation used Zeff = 1.36 at UHR

  6. Measured Trad at 25 GHz from 2fce On-Axis, & 3fce Off-axis; Harmonic Mix Sensitive to EBW n// • Radial access between 2fce & 3fce sensitive to EBW n// due to EC resonance Doppler broadening EBW Ray Tracing

  7. Collisional Loss at Upper Hybrid Resonance (UHR) May Explain Low Measured EBW Trad Measured Trad Simulated Trad with no collisions Simulated Trad with Zeff = 3 at UHR Simulated Trad with Zeff = 5 at UHR • Measured EBW coupling efficiency (Trad/Te) ~ 20% • Emission polarization agrees with simulation • Te ~ 10-30 eV near UHR • Collisional losses can be significant for Te < 30 eV: - EBW conversion efficiency sensitive to Zeff at low Te 1000 Shot = 117970 Frequency = 25 GHz Trad(keV) Measured Emission Polarization (Epara/Eperp) Polarization From Simulation Time (s)

  8. XP514 Summary • Completed first measurements of 2nd harmonic EBW coupling to O-mode from H-mode NSTX plasmas • Coupling efficiency only ~ 20%: - modeling indicates low Te & Zeff ~ 3 at UHR can cause significant EBW collision loss at UHR - ~ 80% fundamental EBW coupling from L-mode NSTX plasmas last year; higher Te at UHR - still analyzing EBW emission data obtained during other experiments during 2005 run • Detailed 8-40 GHz thermal EBW emission coupling study on NSTX in 2006-7 with two remotely-steered antennas

More Related