Overblik over fusionsdiagnostikker. Poul Kerff Michelsen
16/11/20102Risø 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
16/11/20103Risø DTU, Technical University of Denmark
16/11/20104Risø DTU, Technical University of Denmark Tokamakken Magnetspoler til toroidalfeltet Plasma og også den sekundære vikling TransformerjernkerneMagnetfeltlinje Primær vikling
16/11/20105Risø DTU, Technical University of Denmark Magnetiske felter som kan holde et plasma i ligevægt
16/11/20106Risø 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
16/11/20107Risø DTU, Technical University of Denmark
16/11/20108Risø DTU, Technical University of Denmark Karakteristiske parametre for JET og ITER PlasmaparametreJETITER Power Plant Storradius2,96 m6,20 m 6 – 10 m Lilleradius1,25 m x 2,10 m2,0 m x 3,3 m 2 – 3,5 m Plasmalevetid20 s>300 s lang Plamavolumen150 m m m 3 Plasma tæthed10 20 m ,1 - 1, Temperatur20 keV 12 – 22 keV Magnetfelt3,4 T5,3 T 5,5 – 7 T Plasmastrøm4,8 MA15 MA 15 – 30 MA Opvarmningseffekt25 MW75 MW 70 – 270 MW Fusionseffekt16 MW MW 2,5 – 5 GW Q-value0,
16/11/20109Risø DTU, Technical University of Denmark Måling af strøm
16/11/201010Risø DTU, Technical University of Denmark Måling af strøm
16/11/201011Risø DTU, Technical University of Denmark Rogowskispole
16/11/201012Risø DTU, Technical University of Denmark Strøm og spænding
16/11/201013Risø DTU, Technical University of Denmark Langmuir probe
16/11/201014Risø DTU, Technical University of Denmark Edge T e and n e : Langmuir probes Langmuir Probes The first diagnostic in plasma physics (1920’s) The simplest….simply a wire inserted in the plasma! Ion saturation current density Electron collection DITE Tokamak S. Pitcher, 1987
16/11/201015Risø DTU, Technical University of Denmark laserlys elektron Doppler- frekvens- skift Frekvens Intensitet Bredden giver elektrontemperaturen Måling af elektrontemperatur v.h.a. Thomson spredning
16/11/201016Risø DTU, Technical University of Denmark Thomson scattering at JET
16/11/201017Risø 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!
16/11/201018Risø DTU, Technical University of Denmark Range of measurements
16/11/201019Risø DTU, Technical University of Denmark Brydningsindeks for plasma
16/11/201020Risø DTU, Technical University of Denmark Microwave diagnostics: Electron Cyclotron Emission Magnetic field B Electron gyration Electron Cyclotron Emission (ECE) 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,…)
16/11/201021Risø DTU, Technical University of Denmark Resonances and cut-offs Ece Reflectometry
16/11/201022Risø DTU, Technical University of Denmark
16/11/201023Risø DTU, Technical University of Denmark Resonances and cut-offs Ece Reflectometry
16/11/201024Risø DTU, Technical University of Denmark Electron Cyclotron Emission => n*f(Te)
16/11/201025Risø DTU, Technical University of Denmark Microwave diagnostics: ECE and T e during sawteeth 1. Time traces 2. T e - profiles 3. 2D-evolution Tore Supra; V.S. Udintsev et al., PPCF 2005
16/11/201026Risø DTU, Technical University of Denmark Microwave diagnostics: reflectometry Density profiles (Tore Supra) Principles
16/11/201027Risø 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
16/11/201028Risø 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)
16/11/201029Risø DTU, Technical University of Denmark Laser Interferometer
16/11/201030Risø DTU, Technical University of Denmark
16/11/201031Risø DTU, Technical University of Denmark Stark splitting
16/11/201032Risø DTU, Technical University of Denmark
16/11/201033Risø 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.
16/11/201034Risø 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
16/11/201035Risø DTU, Technical University of Denmark NBI Charge eXchange Recombination Spectroscopy Principle of CXRS D pl + + H NBI 0 D pl 0 + H NBI + + h Lines of sights
16/11/201036Risø DTU, Technical University of Denmark CXRS Example of TEXTOR spectrum - Beam density (atten.) - Localisation - Density fluctuations - B-field - MSE (q) - H/D/T ratio - T i bulk - Fast ions
16/11/201037Risø DTU, Technical University of Denmark CXRS Active 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 T i usually from CVI H coupled to D with external H/(H+D) if available
16/11/201038Risø DTU, Technical University of Denmark CXRS Determination of D/T ratio in ITER •Advantages: –Full H/D/T profile can be obtained (resolution of a/30) –Localized measurements (overlap LOS & NBI) –Additional information can be obtained (T i, v tor, NB density, B- field, q profile, …) •Drawback: –Large beam attenuation in ITER reduces signal –Spectra are very complicated –Large Brehmsstrahlung background Large uncertainty (to be quantified) NB modulation allows better discrimination
16/11/201039Risø 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 2008 V.S. Udintsev et al., PPCF 2008
16/11/201040Risø DTU, Technical University of Denmark Neutron and gamma
16/11/201041Risø DTU, Technical University of Denmark Collective Thomson Scattering Principle and geometry kk Incident radiation Received scattered radiation ksks kiki Resolved fluctuations Receiver Probe CTS is based on scattering of injected microwaves on microscopic collective fluctuations in the plasma – e.g. caused by energetic ions
16/11/201042Risø DTU, Technical University of Denmark CTS Spectral power density The spectral information is contained in the scattering function Σ Example of Σ for a standard fast ion geometry at TEXTOR (k δ, 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
16/11/201043Risø DTU, Technical University of Denmark Cyclotron radiation and CTS
16/11/201044Risø DTU, Technical University of Denmark CTS Sensitivity to ion Bernstein waves For geometries with (k δ, B) near 90˚ the CTS spectrum is sensitive to ion Bernstein waves
16/11/201045Risø DTU, Technical University of Denmark CTS Sensitivity of IBW spectrum to fuel ion ratio Model spectra for a TEXTOR H-D plasma at two different ratios
16/11/201046Risø DTU, Technical University of Denmark CTS First 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
16/11/201047Risø DTU, Technical University of Denmark CTS Possible D/T-ratio measurements on ITER Described in the final report of EFDA Contract 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 Z eff σ Ri • 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
16/11/201048Risø DTU, Technical University of Denmark Diganostics på JET
16/11/201049Risø DTU, Technical University of Denmark ITER diagnostics: practically everywhere! C. Walker, 2008