Delgado-Aparicio_APS_April_2010_v2 by qingyunliuliu

VIEWS: 8 PAGES: 35

									           NSTX                            Supported by



                     Multi-energy SXR imaging
College W&M
Colorado Sch Mines
Columbia U
                     for magnetically confined                                                                  Culham Sci Ctr
                                                                                                                 U St. Andrews


                           fusion studies
CompX                                                                                                                     York U
General Atomics                                                                                                        Chubu U
INEL                                                                                                                    Fukui U
Johns Hopkins U                                                                                                    Hiroshima U
LANL                                                                                                                   Hyogo U
LLNL
                                                                                                                        Kyoto U

                             Luis F. Delgado-Aparicio
Lodestar
                                                                                                                      Kyushu U
MIT
                                                                                                               Kyushu Tokai U
Nova Photonics

                       Princeton Plasma Physics Laboratory
                                                                                                                            NIFS
New York U
Old Dominion U                                                                                                         Niigata U
ORNL                                                                                                                    U Tokyo
PPPL                                                                                                                       JAEA
PSI
Princeton U
                                       APS – April meeting,                                                           Hebrew U
                                                                                                                       Ioffe Inst
Purdue U                               Washington, DC, USA                                                  RRC Kurchatov Inst

                                       February, 12-17, 2010
SNL                                                                                                                      TRINITI
Think Tank, Inc.                                                                                                            KBSI
UC Davis                                                                                                                  KAIST
UC Irvine                                                                                                            POSTECH
UCLA                                                                                                                      ASIPP
UCSD                                                                                                           ENEA, Frascati
U Colorado                                                                                                    CEA, Cadarache
U Illinois                                                                                                          IPP, Jülich
U Maryland
                                                                                                                 IPP, Garching
U Rochester
                                                                                                             ASCR, Czech Rep
U Washington
                                                                                                                      U Quebec
U Wisconsin


 NSTX                    APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010
              In collaboration with…


              K. Tritz, D. Stutman,
           M. Finkenthal and D. Kumar
        Plasma Spectroscopy Group (PSG)
       The Johns Hopkins University (JHU)

               M. Bitter and K. Hill
       Princeton University Plasma Physics
                Laboratory (PPPL)

NSTX          APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   2
                                      Outline

 1.    Introduction and motivation

 1.    Main diagnostic and multi-energy technique

 2.    Applications

 1.    Diagnostic improvements and development of
       new edge and core systems

 1.    Summary

NSTX           APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   3
   Magnetic fusion schemes = harsh environment

         Tokamak
                                                   Plasma measurements in harsh
 (toroidalnaya kamera –
                                                  environment are quite a challenge
  magnitnaya katushka)
                                                               1. Hot plasma temperatures

                                                                  2.Fast charged particles

                                                                 3.Strong plasma currents

                                                        4.High magnetic fields & EM-noise

                                                                   5.100’s keV – MeV ions

                                                                         6.MeV neutrons

                                                                          7.Gamma rays

NSTX             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   4
   Motivation for the development of Multi-Energy
            Soft X-ray (ME-SXR) systems

        1. The motivation for the construction of ME-SXR arrays is the
          development of versatile diagnostics which can serve a wide range
          of MCF experiments for a number of critical simultaneous profile
                                   measurements.

                    2.   Useful in a wide variety of applications.

       1.     Compared to magnetic measurements at the wall, the ME-SXR
            technique has advantages for low-f MHD detection, such as spatial
                   localization and insensitivity to stray magnetic fields.

   1.       Evaluate discrepancies between Thomson Scattering and Electron
                Cyclotron Emission diagnostics for electron temperature
                                     measurements


NSTX                     APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   5
                                      Outline

 1.    Introduction and motivation

 1.    Main diagnostic and multi-energy technique

 2.    Applications

 1.    Diagnostic improvements and development of
       new edge and core systems

 1.    Summary

NSTX           APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   6
    1st prototype: multi-energy “optical” SXR array


  NSTX
   Top
  view




 L. Delgado-Aparicio, et al.,
    RSI, 75, 4020, (2004).
  JAP, 102, 073304 (2007).
   PPCF, 49, 1245 (2007).
   NF, 49, 085028, (2009).

NSTX                            APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   7
“Description” of multi-energy/multi-color technique

                             Synthetic X-ray Spectrum




       Probe the slope of the continuum:
NSTX              APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   8
    1st prototype: multi-energy “optical” SXR array


  NSTX
   Top
  view




 L. Delgado-Aparicio, et al.,
    RSI, 75, 4020, (2004).
  JAP, 102, 073304 (2007).
   PPCF, 49, 1245 (2007).
   NF, 49, 085028, (2009).

NSTX                            APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   9
  Principle of the “optical” soft x-ray (OSXR) array
                   Conversion of XUV emission to visible light
                            - r a from f r o m
                           XX-rays y s NSTX plasmaNS T X p l a s m a
                                  (vacuum side)a c c u m
                                          ( v            s i de )
                                                                            vacuum
                                                              F Fiber optic o p t i c v a c c u m
                                                                i ber
                 2 0m CsI:Tls I : T l
                 20         C                                     window (FOW) ( F O W )
                                                                    wi n d o w
                   epos i
                 d deposition t i o n



                                                 i s i light      l i
                                                VVisible b l esystem g h t s y s t e m
                        = 5 nm0
                         =550 5               nm              (
                                                       (airside)a i r s i d e )

                          To discrete channels and light
                    detectors (PMT, APD, Image intensifier)
                            + (RC/TIA) amplifiers

 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<Eph<10 keV) to visible green light (~550 nm).
NSTX                   APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   10
                                      Outline

 1.    Introduction and motivation

 1.    Main diagnostic and multi-energy technique

 2.    Applications

 1.    Diagnostic improvements and development of
       new edge and core systems

 1.    Summary

NSTX           APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   11
       a) Plasma heating using RF waves


                                                                                   • Laser-based TS
                                                                                     system probes
                                                                                    the plasma every
                                                                                        ~ 16 ms.

                                                                                    • Three ME-SXR
                                                                                   emissivities appear
                                                                                      to be different
                                                                                  (different sensitivity
                                                                                       to ne and Te).

                                                                                   • Fill in between
                                                                                  Thomson scattering
                                                                                    measurements!


NSTX        APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)      February, 12-17th, 2010   12
Te0~4keV in between Thomson Scattering time slices

                                                                                     • Fill in between
                                                                                         Thomson
                                                                                         scattering
                                                                                      measurements!

                                                                                     • Error bars: 50-
                                                                                          80 eV

                                                                                     • Application to
                                                                                     RF heating heat
                                                                                        deposition
                                                                                         studies.
                                                                                L. Delgado-Aparicio, et al., JAP,
                                                                                      102, 073304 (2007).

                                                                                    L. Delgado-Aparicio, et al.,
                                                                                      PPCF, 49, 1245 (2007).


NSTX          APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)          February, 12-17th, 2010   13
b) Impurity transport is one of the challenges facing
             the current fusion research
           ITER
       tungsten walls                   For instance: Tungsten, is an attractive candidate
                                              as fusion wall material due to its very high
                                             melting point and high thermal conductivity.

                                          Nevertheless it can melt within one millisecond
                                               when in direct contact with the plasma.




NSTX                    APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   14
 Adding an extrinsic impurity for transport studies




NSTX          APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   15
       Example: ion-gyroradius scan at fixed q-profile



 Ne puff                                       Ne puff                                               Ne puff




L. Delgado-Aparicio, et al., PPCF, 49, 1245 (2007).

NSTX                           APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)        February, 12-17th, 2010   16
  Reproducible properties in subsequent plasmas
           Plasma current,
                                                                            Controlled experiment reproduced
       NBI heating and q-profile
                                                                              elongation and triangularity




NSTX                         APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   17
Example of experimental and simulated SXR profiles




L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).

NSTX                             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   18
    Penetration of impurities changed at high fields




L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).

NSTX                             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   19
   Experimental diffusivity in good agreement with
                 theoretical models




Note large increase in Dneo and Dexp at r/a>0.8
L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).

NSTX                             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   20
           Convective velocity changes sign with BT




       VZ<0 at r/a>0.5 at low-field is anomalous ⇒ instabilities?

L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).

NSTX                             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   21
    c) Resistive Wall Mode (RWM) research in NSTX

•   RWM is an external kink modified by                        Passive                                          RWM
    presence of resistive wall.                                 plates                                        Sensors (Br)

                                                                                                               RWM
                                                        RWM active
•   RWM Characteristics:                                                                                     Sensors (Bp)
                                                        stabilization
     – slow growth: G ≲ 1/twall
                                                            coils
     – slow rotation: fRWM ≲ 1/2ptwall
     – twall~5-10 ms
     – stabilized by rotation & dissipation

•   High toroidal rotation passively stabilizes
    RWM at high-q.

•   RWM can affect both the outer and inner
    plasma.

•   Long-pulse, high-bN requires stabilization.                         (exterior view)                    (interior view)
                                                                          S. A. Sabbagh, et al., NF, 46, 635, (2006).
NSTX                      APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)     February, 12-17th, 2010    22
Actively-stabilized RWM plasmas show n=1 mode




NSTX       APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   23
ME-SXR reconstructions indicate n=1 stable mode
                                                                                                  Fast SXR-based Te(R,t)
                                                                                                       measurements




       L. Delgado-Aparicio, et al., to be submitted, NF (2010).
NSTX                             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)     February, 12-17th, 2010   24
       d) Pressure (b) -collapse and plasma recovery




  • Three ME-SXR emissivities have different sensitivity to ne and Te.
         •All arrays are sensitive to the peripheral and core Te crash.
NSTX                  APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   25
            Fast Te(R,t) estimate for b-collapse




        • 0th order approx. since b collapse is not axysimmetric.

       • Te,core~200 eV , Te,mid-radius~600 eV and Te,edge~300 eV.

                      L. Delgado-Aparicio, et al., to be submitted, NF (2010).
NSTX                APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010
                                      Outline

 1.    Introduction and motivation

 1.    Main diagnostic and multi-energy technique

 2.    Applications

 1.    Diagnostic improvements and development of
       new edge and core systems

 1.    Summary

NSTX           APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   27
            Room for “desirable” improvement

  1. Increase spatial resolution (from present 4 cm to 1 cm)
                a) Particle transport at the edge: D~q2
                   b) Resolve edge plasma profiles
                c) Observe cooling of NTM O-points.

         2. Increase spectral resolution (# of SXR filters)
           a) Better constraint for Te(R,t) measurements.
   b) Thinner filters will allow measurements/imaging of pedestal &
            gradient region using continuum & line emission.

       3. Increase number of ME-SXR cameras for study of
            non-axisymmetric perturbations (3D-effects).

NSTX               APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   28
        Edge optical-based ME-SXR system under
            construction for NSTX (2010 run)




       Benefits of optical-based SXR array
       • High spatial resolution (~1 cm)
       • Spatial oversampling
       • Filter/energy band versatility                                                          K. Tritz (JHU)
       • Simple design and components
NSTX                       APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   29
Alternative: edge diode-based fast (>10 kHz) system




       Benefits of diode-based SXR array
       • High dynamic range
       • High bandwidth
       • Modular components                                                                       K. Tritz (JHU)
       • Compact detector and electronics
NSTX                        APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   30
       Core diode-based system for C-mod & NSTX

Pilatus pixelated photon-counting detectors enable new diagnostics
 • Pilatus: PIxelated Large Area detector.                                                         ~8cm

 • Dectris - Pilatus 100k Module (~100k pixels)
       1. Sensor:         Silicon (320 m) diode array.
       2. Pixels:         172x172 m2 (487x195)
       3. Parameters are adjustable on a per-pixel basis
             • Amplifier, shaper and lower level discriminator
             • Energy Range:         2.5 - 20 keV
             • Area:                 8.4 x 3.4 cm2
             • Count Rate/pixel: < 2x106 x-rays/s
             • Min readout time 2.54 ms
             • Latest version of Pilatus, called “EIGER” has 75 m
               pixel size and ~24 kHz framing rate capability with
               only 1 s dead time between frames.


K. Hill & M. Bitter (PPPL)
NSTX                     APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   31
  Pilatus “pinhole camera” can measure spatially
 resolved broad-band soft x-ray spectra, 2-20 keV
                                                      Concept:
                                                      • Energy resolution ~500 eV FWHM
                                                      • Example: Emin= 2 keV, 2.5, 3, 3.5, 4, 5, 7,
                                                         10 and 14 keV.
                                                      • Few columns (5) at low-energy, where
                                                         count rate is high and many columns (50) at
                                                         high-energy where count rate is lower.
                                                      • Sum 487 rows vertically to form 49 spatial
                                                         sightlines and improve statistics.

                                                      Aplications:
                                                      • Poloidal tomographic reconstructions.
                                                      • Model Max. continuum + lines emission.
                                                      • 2D picture of Te, Zeff, nmetals.
                                                      • Electron thermal and impurity transport.
                                                      • Easy to adapt to different tokamak sizes.
K. Hill & M. Bitter (PPPL)
NSTX                   APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   32
                                               Summary
1.      The motivation for the construction of ME-SXR arrays is the development
        of versatile diagnostics which can serve a wide range of MCF
        experiments for a number of critical simultaneous profile measurements.

2.      Useful in a wide variety of applications: a) RF heating, b) particle
        transport, c) thermal transport and d) a variety of MHD events.

3.      Compared to magnetic measurements, the ME-SXR technique has
        advantages for low-f MHD detection, such as spatial localization and
        insensitivity to stray magnetic fields.

4.      The use of thinner filters will allow imaging and measurements of
        pedestal & gradient regions using continuum and impurity line-emission.

5.      Recommend the use of few ME-SXR cameras (tangential/poloidal views)
        in multiple toroidal locations for study of non-axisymmetric
        perturbations. APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)          th
 NSTX                                                                                      February, 12-17 , 2010
                                                                                                                33
                        Acknowledgements (I)

 The Johns Hopkins University (JHU)                                       Columbia University (CU)
  Plasma Spectroscopy Group (PSG)                                         S. A. Sabbagh, J. Berkekey,
        K. Tritz, D. Stutman,                                              J. Bialek and J. Levesque
     M. Finkenthal and D. Kumar
                                                                       Oak Ridge National Laboratory
 Princeton University Plasma Physics                                               (ORNL)
             Laboratory (PPPL)                                             R. Maingi, J.M. Canik
   R. Bell, M. Bitter, W. Blanchard,                                          and A.C. Sontag
E. Fredickson, S. P. Gerhard, K. Hill, J.
  Hosea, R. Kaita, S. Kaye, B. LeBlanc,                                              Nova Photonics
      J. Manickam, J. Menard, C. K.                                                     H. Yuh
   Phillips, L. Roquemore, W. Solomon
               and B. Stratton
                                                                     University of Wisconsin-Madison
                                                                                  F. Volpe



NSTX                   APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   34
                 Acknowledgements (II)

• The Johns Hopkins University: Gaib Morris, Scott Spangler,
  Steve Patterson, Russ Pelton and Joe Ondorff.

• Princeton Plasma Physics Laboratory: Bill Blanchard, Patti
  Bruno, Thomas Czeizinger, John Desandro, Russ Feder, Jerry
  Gething, Scott Gifford, Bob Hitchner, 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




NSTX             APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio)   February, 12-17th, 2010   35

								
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