Post on 31-Mar-2015
Overblik over fusionsdiagnostikker.
Poul Kerff Michelsen
16/11/20102 Risø DTU, Technical University of Denmark
Oversigt• Introduktion• Tokamakken• Typiske værdier plasma parametre• Strøm-spændingsmålinger• Langmuirprobe• Brydningsindeks/dielektritetskonstanten• Andre tætheds- og temperaturmålinger• Tæthed- og temperaturprofiler• Andre diagnostikker
16/11/20103 Risø DTU, Technical University of Denmark
16/11/20104 Risø DTU, Technical University of Denmark
Tokamakken
Magnetspoler til toroidalfeltet
Plasma og også den sekundære
vikling TransformerjernkerneMagnetfeltlinje
Primærvikling
16/11/20105 Risø DTU, Technical University of Denmark
Magnetiske felter som kan holde et plasma i ligevægt
16/11/20106 Risø DTU, Technical University of Denmark
Ligevægt og stabilitet
• Et toroidaltformet plasma kan være ustabilt på mange måder. De fleste af disse ”instabiliteter” er forstået teoretisk og kan kontroleres, men de sætter grænser for den maksimale plasmatæthed og det maksimale plasmatryk
16/11/20107 Risø DTU, Technical University of Denmark
16/11/20108 Risø DTU, Technical University of Denmark
Karakteristiske parametre for JET og ITER
Plasmaparametre JET ITER Power Plant
Storradius 2,96 m 6,20 m 6 – 10 m
Lilleradius 1,25 m x 2,10 m 2,0 m x 3,3 m 2 – 3,5 m
Plasmalevetid 20 s >300 s lang
Plamavolumen 150 m3 828 m3 1000 - 4000 m3
Plasma tæthed 1020 m-1 1020 1,1 - 1,4 1020
Temperatur 20 keV 20 keV 12 – 22 keV
Magnetfelt 3,4 T 5,3 T 5,5 – 7 T
Plasmastrøm 4,8 MA 15 MA 15 – 30 MA
Opvarmningseffekt 25 MW 75 MW 70 – 270 MW
Fusionseffekt 16 MW 200 - 700 MW 2,5 – 5 GW
Q-value 0,65 6 - 15 15 - 35
16/11/20109 Risø DTU, Technical University of Denmark
Måling af strøm
16/11/201010 Risø DTU, Technical University of Denmark
Måling af strøm
16/11/201011 Risø DTU, Technical University of Denmark
Rogowskispole
16/11/201012 Risø DTU, Technical University of Denmark
Strøm og spænding
16/11/201013 Risø DTU, Technical University of Denmark
Langmuir probe
16/11/201014 Risø DTU, Technical University of Denmark
Edge Te and ne: Langmuir probes
Langmuir Probes
The first diagnostic in plasma physics (1920’s)
The simplest….simply a wire inserted in the plasma!
Ion saturationcurrent density
Electron collection
DITE Tokamak
S. Pitcher, 1987
16/11/201015 Risø DTU, Technical University of Denmark
• laserlys• elektr
on• Doppler-frekvens-skift
Frekvens
IntensitetBredden giver elektrontemperaturen
Måling af elektrontemperatur v.h.a. Thomson spredning
16/11/201016 Risø DTU, Technical University of Denmark
Thomson scattering at JET
16/11/201017 Risø DTU, Technical University of Denmark
Laser-aided diagnostics: Thomson scattering
The monochromatic laser light is scattered and Doppler-shifted by the moving plasma electrons producing a broad spectrum of scattered light
Thomson scattering: exists also for divertor!
16/11/201018 Risø DTU, Technical University of Denmark
Range of measurements
16/11/201019 Risø DTU, Technical University of Denmark
Brydningsindeks for plasma
)½(),½(
af funktionerer og ,
cos4sin)(
)cos1(sin
cossin
2
:ndexBrydningsi
222422
22
22
2
LRDLRS
PLR
DPPSRLF
PSRLB
PSA
A
FBn
c
k
n
16/11/201020 Risø DTU, Technical University of Denmark
Microwave diagnostics: Electron Cyclotron Emission
ece m
eB
Magnetic field BElectron
gyrationElectron Cyclotron Emission
(ECE)
eB
ce Tkc
nI
ce 2
2
Typical Instruments:• Radiometers (JET, Tore Supra, JT-60U, DIII-D, AUG, TJ-II, TCV, TEXTOR, RTP, TEXT-U, T-
10, HT-7,…)• Michelson interferometers (TFTR, FTU, JET, DIII-D,…)
16/11/201021 Risø DTU, Technical University of Denmark
Resonances and cut-offsEceReflectometry
0
0,5
1
1,5
2
2,5
-1 -0,5 0 0,5 1
position
freq
uen
cy
16/11/201022 Risø DTU, Technical University of Denmark
16/11/201023 Risø DTU, Technical University of Denmark
Resonances and cut-offsEceReflectometry
0
0,5
1
1,5
2
2,5
-1 -0,5 0 0,5 1
position
freq
uen
cy
16/11/201024 Risø DTU, Technical University of Denmark
Electron Cyclotron Emission => n*f(Te)
16/11/201025 Risø DTU, Technical University of Denmark
Microwave diagnostics: ECE and Te during sawteeth
1. Time traces2. Te - profiles
3. 2D-evolution
Tore Supra;
V.S. Udintsev et al., PPCF 2005
16/11/201026 Risø DTU, Technical University of Denmark
Microwave diagnostics: reflectometry
Density profiles (Tore Supra)
Principles
16/11/201027 Risø DTU, Technical University of Denmark
Microwave diagnostics: ECE-Imaging, NTM control,…
ECE-Imaging: TEXT-U, RTP, TEXTOR, AUG,…
H Park et al., RSI 75, 3787 (2004); PRL 2006
NTM Control: AUG, TEXTOR, TCV,…
N. Hicks et al., EPS 2008
ECE imaging measurements and simulations for sawtooth in TEXTOR
16/11/201028 Risø DTU, Technical University of Denmark
Laser-aided diagnostics: interferometry
Interferometry measures the line-averaged electron density by comparing the phase change of two waves, one traveling through the plasma, and another through the vacuum or air.
Several viewing chords allow obtaining the profiles across the plasma.
Can also be a mm-wave diagnostic (TCV)!
Interferometry on TEXTOR(Koslowski, Fus. Eng. Des. 1995)
16/11/201031 Risø DTU, Technical University of Denmark
Stark splitting
16/11/201032 Risø DTU, Technical University of Denmark
L1
L2BS
interference filter
L5
HD-Geissler-
tube
L4 echelle grating
f
fibre
Echelle spectrometer in Littrow arrangement
Focal length f=1 mObseravtion: 2nd orderGrating: 600 l/mmResolving Power: R>12000f=20 Hz
L5
M
CCD
16/11/201033 Risø DTU, Technical University of Denmark
Balmer spectrum
with line of sight on
the main toroidal belt limiter
Cold component
from molecules
(recycling flux)
Hot component
from CXRS etc.
16/11/201034 Risø DTU, Technical University of Denmark
Spectroscopy and particle diagnostics – CXRS
The beam neutral atoms can loose their electron to any ion of the high-temperature plasma. The getter ion then emits a series of spectral lines including visible and ultraviolet lines.
Spectroscopy of these lines enables us to measure the temperature of the getter ions from the Doppler broadening of the lines.
TCV DNBI; courtesy A. Karpushov, Ch. Schlatter, B.P. Duval
D. Thomas, FST 2008
16/11/201035 Risø DTU, Technical University of Denmark
NBI
Charge eXchange Recombination SpectroscopyPrinciple of CXRS
Dpl+ + HNBI
0 Dpl0 + HNBI
+ + hn
Lines of sights
16/11/201036 Risø DTU, Technical University of Denmark
CXRSExample of TEXTOR spectrum
- Beam density (atten.) - Localisation- Density fluctuations- B-field- MSE (q)
- H/D/T ratio- Ti bulk- Fast ions
16/11/201037 Risø DTU, Technical University of Denmark
CXRSActive beam spectroscopy of the H/D ratio
Complicated!!
E/1E/2
E/3
CII multiplet (10 Zeeman components: ADAS603)
Cold H/Dalpha features(usually overexposed)neglected in fit
Dα-PCX(Gaussian)
Dα –CX (Gaussian) initial estimate Ti usually from CVI
H coupled to D with external H/(H+D) if available
16/11/201039 Risø DTU, Technical University of Denmark
Spectroscopy and particle diagnostics – Soft X-Ray
TCV: multi-chord cameras, such as X-ray diodes, with thin Beryllium filters
Tomography reconstruction (together with modelling)
G. Turri et al., PPCF 2008V.S. Udintsev et al., PPCF 2008
16/11/201040 Risø DTU, Technical University of Denmark
Neutron and gamma
16/11/201041 Risø DTU, Technical University of Denmark
Collective Thomson ScatteringPrinciple and geometry
k
Incident radiation
Received scattered radiation
ks
kiResolved fluctuations
ReceiverProbe
CTS is based on scattering of injected microwaves on microscopic collective fluctuations in the plasma – e.g. caused by energetic ions
16/11/201042 Risø DTU, Technical University of Denmark
CTSSpectral power density
The spectral information is contained in the scattering function Σ
Example of Σ for a standard fast ion geometry at TEXTOR (kδ, B) >100˚ or <80˚
For ITER, CTS has mainly been developed as a fast ion diagnostic, enabling spatio-temporally resolved measurements of the velocity distribution of confined fast ions
16/11/201043 Risø DTU, Technical University of Denmark
Cyclotron radiation and CTS
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
-1 -0,8 -0,6 -0,4 -0,2 0 0,2 0,4 0,6 0,8 1
position
freq
uen
cy
16/11/201044 Risø DTU, Technical University of Denmark
CTSSensitivity to ion Bernstein waves
For geometries with (kδ, B) near 90˚ the CTS spectrum is sensitive to ion Bernstein waves
16/11/201045 Risø DTU, Technical University of Denmark
CTSSensitivity of IBW spectrum to fuel ion ratio
Model spectra for a TEXTOR H-D plasma at two different ratios
16/11/201046 Risø DTU, Technical University of Denmark
CTSFirst results of proof-of-principle diagnostic
Green: resolved angle not perpendicular
Blue: resolved angle approx 89˚
Distance between peaks is ~20 MHz – corresponding to the cyclotron frequency of Deuterium at 2.6 T
16/11/201047 Risø DTU, Technical University of Denmark
CTSPossible D/T-ratio measurements on ITER
Described in the final report of EFDA Contract 04-1213 - deliverable 4.1- D3
Derivative of the spectral power density of the CTS spectrum with respect to the fuel ion ratio for an ITER diagnostic Spectrum is sensitive to D/T-ratio
Zeff 1.82 2.37 4.60
σRi 0.146 0.151 0.138
• Possibly separate low power probe – 10 kW
• Temporal resolution of 100 ms
• Spatial resolution of a/10 across the full radius
• Uncertainty: STD ~ 0.15
• Limited influence of impurity content
• Not part of the ITER baseline design
16/11/201048 Risø DTU, Technical University of Denmark
Diganostics på JET
16/11/201049 Risø DTU, Technical University of Denmark
ITER diagnostics: practically everywhere!
C. Walker, 2008