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APS-DPP-2005-LeBlanc-1 Update on MPTS B.P. LeBlanc Princeton Plasma Physics Laboratory NSTX Results Review July 26-27, 2006 Princeton, NJ.

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Presentation on theme: "APS-DPP-2005-LeBlanc-1 Update on MPTS B.P. LeBlanc Princeton Plasma Physics Laboratory NSTX Results Review July 26-27, 2006 Princeton, NJ."— Presentation transcript:

1 APS-DPP-2005-LeBlanc-1 Update on MPTS B.P. LeBlanc Princeton Plasma Physics Laboratory NSTX Results Review July 26-27, 2006 Princeton, NJ

2 APS-DPP-2005-LeBlanc-2 Tasks Performed Recently Install new hardware –10 polychromators, 40 preamplifiers and ancillary electronics Comprehensive calibration of existing hardware and new hardware –Spectral calibration of each polychromator New optical configuration –APD gain vs. high voltage Typical gains –Fast- and slow-electronics’ transfer function Relates fast data (TS/Rayleigh/Raman) to slow data (calibration) –Rayleigh and Raman calibration Software update

3 APS-DPP-2005-LeBlanc-3 Ten new channels instrumented with 4-wavelength GA polychromators and EG&G APD’s with PPPL preamplifiers PPPL preamplifier Slow signal output Fiber bundle Fast signal output GA polychromator Control signals

4 APS-DPP-2005-LeBlanc-4 New Radial Channel Allocation Enhance outer edge resolution8 channels Better inner resolution2 channels Split – for the first time – the output end of a fiber bundle to improve spatial resolution Inner split bundle R =143.6cm±0.5cm Outer split bundle R =144.5 cm±0.5cm

5 APS-DPP-2005-LeBlanc-5 n e Profile Calibration Phases I and II polychromators have 6 spectral channels, including one at Rayleigh wavelength –So far n e calibration done with Rayleigh scattering –But could also be done with Raman scattering Phase III polychromators have 4 spectral channels, but none at Rayleigh wavelength – n e profile calibration with Raman scattering Since Rayleigh signal is much larger than Raman, need to ascertain extinction ratio of Rayleigh light at Raman spectral location.

6 APS-DPP-2005-LeBlanc-6 Extinction for Ratio Phase III Extinction ratio for 1064-nm light through 1053-nm filter Significant amount of Rayleigh light enters the 1053-nm filter Existing channels

7 APS-DPP-2005-LeBlanc-7 Raw Data Acquired Phase III hardware has acquired data for during the last two NSTX experimental runs Raw data signals –Top: fast signal (Thomson scattering) –Bottom: slow signal (plasma light)

8 APS-DPP-2005-LeBlanc-8 Data Analysis 30-channel vs. existing 20 channels New calibration of existing 20 channels –Good match to previous calibration –Slightly higher temperature for T e > 2 keV New channels’ analysis unsatisfactory –Systematic error corroborated by large  2 Black: old 20-ch calibration Red: new 20-ch calibration Arrows: new channels

9 APS-DPP-2005-LeBlanc-9 Correction Factors Computed from exiting adjacent channels Appear independent of Te Appear independent of APD high voltage Suggest problem might be optical

10 APS-DPP-2005-LeBlanc-10 Other Tasks to be Done Fix the new channels –Investigate optical issue with new polychromators –Pursue density calculation and scaling, which might reveal relevant issues –Compute 30-point profiles and load tree Improve laser delivery optics –Eliminate n e l time modulation associated with lasers Procure and install polarizer on viewing optics –Eliminate needs to close one view-optics shutter at high density

11 APS-DPP-2005-LeBlanc-11 MPTS Implementation MPTS is a multi-time multi-spatial point Thomson scattering diagnostic, which routinely provides T e (R,t) and n e (R,t). So far two 30-Hz Nd:YAG lasers 36 fiber bundles already viewing plasma –Output end can be split for improved resolution Phased implementation –Phase I60 Hz10 channels –Phase II60 Hz 20 channels –Phase III60 Hz 30 channels

12 APS-DPP-2005-LeBlanc-12 Polychromator 206 Focal decentration

13 APS-DPP-2005-LeBlanc-13 Collecting Optics 29 out of 36 fiber bundles instrumented Laser beam (LB), laser tube (LT), TF coil (TF), focal point (FP), primary mirror (PM), aperture stop (AS), image of laser path (IM), fiber bundle (FB), plasma edge (PE), major radius (R), center stack (CS), vacuum window (VW) Fiber bundle holder 36 bundles in place Vacuum Window


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