multi-energy sxr imaging for magnetically confined fusion studies
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NSTX. Supported by. Multi-energy SXR imaging for magnetically confined fusion studies. College W&M Colorado Sch Mines Columbia U CompX General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U Purdue U SNL - PowerPoint PPT PresentationTRANSCRIPT
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
Multi-energy SXR imaging for magnetically confined
fusion studies
Multi-energy SXR imaging for magnetically confined
fusion studies
Luis F. Delgado-AparicioPrinceton Plasma Physics Laboratory
APS – April meeting, Washington, DC, USAFebruary, 12-17, 2010
College W&MColorado Sch MinesColumbia UCompXGeneral AtomicsINELJohns Hopkins ULANLLLNLLodestarMITNova PhotonicsNew York UOld Dominion UORNLPPPLPSIPrinceton UPurdue USNLThink Tank, Inc.UC DavisUC IrvineUCLAUCSDU ColoradoU IllinoisU MarylandU RochesterU WashingtonU Wisconsin
Culham Sci CtrU St. Andrews
York UChubu UFukui U
Hiroshima UHyogo UKyoto U
Kyushu UKyushu Tokai U
NIFSNiigata UU Tokyo
JAEAHebrew UIoffe Inst
RRC Kurchatov InstTRINITI
KBSIKAIST
POSTECHASIPP
ENEA, FrascatiCEA, Cadarache
IPP, JülichIPP, Garching
ASCR, Czech RepU Quebec
NSTXNSTX Supported by
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 2
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. HillPrinceton University Plasma Physics
Laboratory (PPPL)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 3
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 4
Magnetic fusion schemes = harsh environment
Tokamak(toroidalnaya kamera – magnitnaya katushka)
Plasma measurements in harsh environment are quite a challenge
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 5
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 6
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 7
1st prototype: multi-energy “optical” SXR array
L. Delgado-Aparicio, et al.,
RSI, 75, 4020, (2004).
JAP, 102, 073304 (2007).
PPCF, 49, 1245 (2007).
NF, 49, 085028, (2009).
NSTXTopview
Magnetic
axis
(core)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 8
“Description” of multi-energy/multi-color technique
Probe the slope of the continuum:
Synthetic X-ray Spectrum
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 9
1st prototype: multi-energy “optical” SXR array
L. Delgado-Aparicio, et al.,
RSI, 75, 4020, (2004).
JAP, 102, 073304 (2007).
PPCF, 49, 1245 (2007).
NF, 49, 085028, (2009).
NSTXTopview
Magnetic
axis
(core)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 10
Principle of the “optical” soft x-ray (OSXR) array
20 m CsI:Tl deposition
X-rays from NSTX plasma (vaccum side)
Visible light system (air side)
Fiber optic vaccum window (FOW)
=550 nm
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).
To discrete channels and light detectors (PMT, APD, Image intensifier)
+ (RC/TIA) amplifiers
Conversion of XUV emission to visible light
X-rays from NSTX plasma(vacuum side)
Fiber optic vacuumwindow (FOW)20 m CsI:Tl
deposition
Visible light system(airside)=550 nm
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 11
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 12
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!
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 13
Te0~4keV in between Thomson Scattering time slices
L. Delgado-Aparicio, et al., JAP, 102, 073304 (2007).
L. Delgado-Aparicio, et al., PPCF, 49, 1245 (2007).
• Fill in between Thomson scattering
measurements!
• Error bars: 50-80 eV
• Application to RF heating heat
deposition studies.
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 14
b) Impurity transport is one of the challenges facing the current fusion research
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.
ITER tungsten walls
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
Adding an extrinsic impurity for transport studies
15
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 16
Example: ion-gyroradius scan at fixed q-profile
Ne puff Ne puff Ne puff
L. Delgado-Aparicio, et al., PPCF, 49, 1245 (2007).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 17
Reproducible properties in subsequent plasmas
Plasma current, NBI heating and q-profile
Controlled experiment reproduced elongation and triangularity
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 18
Example of experimental and simulated SXR profiles
L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 19
Penetration of impurities changed at high fields
L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 20
Experimental diffusivity in good agreement with theoretical models
L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).
Note large increase in Dneo and Dexp at r/a>0.8
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 21
Convective velocity changes sign with BT
L. Delgado-Aparicio, et al., Nucl. Fusion, 49, 085028, (2009).
VZ<0 at r/a>0.5 at low-field is anomalous instabilities?⇒
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 22
c) Resistive Wall Mode (RWM) research in NSTX
• RWM is an external kink modified by presence of resistive wall.
• RWM Characteristics:
– slow growth: 1/≲ wall
– slow rotation: fRWM 1/2≲ wall
– wall~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-N requires stabilization.(interior view)(exterior view)
S. A. Sabbagh, et al., NF, 46, 635, (2006).
RWM RWM
Sensors (BSensors (Brr))
RWM activeRWM active
stabilizationstabilization
coilscoils
PassivePassive
platesplates
RWM RWM
Sensors (BSensors (Bpp))
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 23
Actively-stabilized RWM plasmas show n=1 mode
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 24
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).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 25
d) Pressure -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.
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
Fast Te(R,t) estimate for -collapse
• 0th order approx. since 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).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 27
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
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
Room for “desirable” improvement
28
1. Increase spatial resolution (from present 4 cm to 1 cm)a) Particle transport at the edge: D~q2
b) Resolve edge plasma profilesc) 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).
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
Benefits of optical-based SXR array• High spatial resolution (~1 cm)• Spatial oversampling• Filter/energy band versatility• Simple design and components
29
Edge optical-based ME-SXR system under construction for NSTX (2010 run)
K. Tritz (JHU)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 30
Alternative: edge diode-based fast (>10 kHz) system
Benefits of diode-based SXR array• High dynamic range• High bandwidth• Modular components• Compact detector and electronics
K. Tritz (JHU)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010
• Pilatus: PIxelated Large Area detector.
• Dectris - Pilatus 100k Module (~100k pixels)1. Sensor: Silicon (320 m) diode array.
2. Pixels: 172x172m2 (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.
31
Core diode-based system for C-mod & NSTX
Pilatus pixelated photon-counting detectors enable new diagnostics ~8cm
K. Hill & M. Bitter (PPPL)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 32
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)
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 33
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.
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 34
Acknowledgements (I)
The Johns Hopkins University (JHU) Plasma Spectroscopy Group (PSG)
K. Tritz, D. Stutman, M. Finkenthal and D. Kumar
Princeton University Plasma Physics Laboratory (PPPL)
R. Bell, M. Bitter, W. Blanchard, E. Fredickson, S. P. Gerhard, K. Hill, J.
Hosea, R. Kaita, S. Kaye, B. LeBlanc, J. Manickam, J. Menard, C.
K. Phillips, L. Roquemore, W. Solomon and B. Stratton
Columbia University (CU)S. A. Sabbagh, J. Berkekey,J. Bialek and J. Levesque
Oak Ridge National Laboratory (ORNL)
R. Maingi, J.M. Canik and A.C. Sontag
Nova PhotonicsH. Yuh
University of Wisconsin-MadisonF. Volpe
NSTXNSTX APS – April 2010, Washington, DC– ME-SXR imaging (Delgado-Aparicio) February, 12-17th, 2010 35
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