1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Page 1 Measurements of Temperature and Density in Magnetic Confinement Fusion Devices Victor Udintsev on behalf of ITER ORGANISATION, Diagnostic Division St. Paul-les-Durance, France Acknowledgements: ITER Diagnostic Division members, ITPA-TGD, TCV Team, TEXTOR Team, Tore Supra Team and many others

Page 2 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Outline  Introduction What is nuclear fusion? Why temperature and density measurements are important?  Overview of methods and results  ITER: the next step in diagnostic advances Diagnostics for density and temperature Major challenges  Outlook: future of fusion diagnostics

Page 3 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, What is nuclear fusion? E = mc 2 FusionFission

Page 4 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Fusion plasma Lawson criterion: nTτ E > keV s m -3 for Q = 1 (break-even) Q = Fusion energy/ Energy put in the plasma Fusion reactor: 1 eV = K

Page 5 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Magnetic confinement fusion devices … Tokamak is the most successful concept of fusion device so far! Magnetic traps Stellarators

Page 6 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Why temperature and density measurements are important? Physics study Plasma control and operation Development of new diagnostics and techniques Knowledge of electron and ion temperature and density, as well as concentration of impurities is essential for ITER and future fusion plant. Key parameters: T e, T i, n e, n i, n t /n d, … and their fluctuations

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Page 8 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Typical diagnostics and techniques Electron temperature (T e ): Electron Cyclotron Emission, Thomson Scattering, Soft X-Ray, Langmuir probes (edge) Electron density (n e ): Thomson scattering, Interferometry, Reflectometry, Soft X-Ray Neutrals/ions temperature and density (T i, n i ): Neutral Particle Analysers, Charge Exchange Recombination Spectroscopy (CXRS), Collective Thomson Scattering (fast ion velocity distribution) Functionality: active or passive Physical principles: microwave, laser-aided, particle,… Location: in-vessel, ex-vessel, divertor,… Diagnostic classifications:

Page 9 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Range of measurements

Page 10 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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,…)

Page 11 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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

Page 12 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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

Page 13 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Microwave diagnostics: reflectometry Density profiles (Tore Supra) Principles

Page 14 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Microwave diagnostics: correlation reflectometry TEXTOR, A. Krämer-Flecken et al., PPCF 51 (2009): Measurement of turbulence properties, poloidal and radial correlation length Measurement of plasma rotation (perpendicular to magnetic field) Estimation of the radial electric field Measurement of correlation length and rotation with the same diagnostic at the same time Find answers on the influence of rotation shear on turbulence (transport)

Page 15 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Microwave diagnostics: reflectometry, ECE and turbulence TEXTOR: Investigation of long range correlations for geodesic acoustic modes by reflectometry DIII-D (White, Peebles): Simultaneous d n & d Te measurement in DIII-D TCV (Udintsev, Fable): TEM observation by Correlation ECE

Page 16 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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!

Page 17 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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)

Page 18 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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

Page 19 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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

Page 20 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, 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

Page 21 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, More to follow at this Conference! Collective Thomson scattering (Korsholm), today Fast particle measurements (Kiptily), today Neutron Emission Spectroscopy (Eriksson), today Non-thermal CXRS (von Hellermann), tomorrow Analysis of JET data (Murari), tomorrow …

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Page 23 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER, the link between today and tomorrow Plasma Volume ~ 100m 3 Fusion Power ~ 16 Mega Watt (JET) Temperature ~ 520 Million C (JT60) Pulse length ~ a few seconds Cu magnets ITER Long burn, Integration of fusion tech., Test of tritium production 850 m MW M°C 400s -> steady state SC magnets Electricity - generating power plant including tritium production similar size 3000 MW M°C steady state ScienceEconomyScience & Technology A. Costley, 2007

Page 24 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Toroidal Field Coil Nb 3 Sn, 18, wedged Central Solenoid Nb 3 Sn, 6 modules Poloidal Field Coil Nb-Ti, 6 Vacuum Vessel 9 sectors Cryostat 24 m high x 28 m dia. Blanket 440 modules Major plasma radius 6.2 m Plasma Volume: 840 m 3 Plasma Current: 15 MA Typical Density: m -3 Typical Temperature: 20 keV Fusion Power: 500 MW Machine mass: t (cryostat + VV + magnets) - shielding, divertor and manifolds: 7945 t port plugs - magnet systems: t; cryostat: 820 t Divertor 54 cassettes ITER, the next step in diagnostic advances

Page 25 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER cross-section

Page 26 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER diagnostics: practically everywhere! C. Walker, 2008

Page 27 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER: temperature and density Electron density and temperature (core): x10 20 m -3 ; keV Electron density and temperature (divertor): < m -3 ; < 0.2 keV Ion temperature (core): keV Ion temperature (divertor): – 0.2 keV Instruments: ECE, Thomson scattering, reflectometry, interferometry, X-ray, probes Instruments: CXRS, Collective Thomson scattering, neutron spectrometers, VUV Impurity density profile Core He density Instruments: CXRS, X-ray cameras

Page 28 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, NEW! Neutron spectrometers 1) Spectroscopy of 14 MeV and 2.5 MeV peaks → - Ion temperature FWHM (  E) ≈ c T i 1/2 - n t /n d fuel ratio (core) Y n 2.45/Y n 14 ≈ c* n t /n d - informations on fast ions population; Diagnostic system: High Resolution Neutron Spectrometers 2) Profile of neutron emission → Ion temperature profile; Diagnostic system: Neutron Cameras (tomography) 3) Spectroscopy + profile → n t /n d fuel ratio profile Diagnostic system: Neutron Cameras with Neutron Spectrometers L. Bertalot, 2009

Page 29 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Neutron measurements: Hi-Res neutron spectrometers Various spectrometers for 2.5 and 14 MeV under consideration

Page 30 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER environment, compared to JET Relative to existing machines, on ITER the diagnostic components will be subject to (relative to JET)  High neutron and gamma fluxes (up to x 10)  Neutron heating (1 MW/m 3 ) (essentially zero)  High fluxes of energetic neutral particles from charge exchange processes (up to x5)  Long pulse lengths (up to x 100)  High neutron fluence (> 10 5 ! ) A. Costley, 2007

Page 31 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, ITER environment: engineering challenges A. Costley, 2007 Consequentially a range of phenomena have to be considered that are new to diagnostic design including:  Radiation-induced conductivity (RIC)  Radiation induced electrical degradation (RIED)  Radiation-induced electromotive force (RIEMF)  Erosion and deposition on mirrors  Radiation induced absorption  Heating  Change in other properties such as activation, transmutation and swelling Moreover, the nuclear environment sets demands on the engineering of the diagnostic systems, for example on neutron shielding, Tritium containment, vacuum integrity, Remote Handling compatibility. Taken together this means that the development of diagnostics for ITER is the most difficult challenge ever undertaken in high temperature plasma diagnostics.

Page 32 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Example: Divertor Plasma, n e & T e measurement –Divertor Thomson: n e, T e –Interferometer: n e –Langmuir probes: n e, T e Challenges: alignment, impurity deposition on mirrors, integration, handling Ph. Andrew, 2009

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Page 34 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, Future of fusion diagnostics ITER is not an end in itself: it is the bridge toward a first plant that will demonstrate the large-scale production of electrical power and Tritium fuel self-sufficiency. This is the next step after ITER: the Demonstration Power Plant, or DEMO. Temperature and density measurements will play a key role in the development of future power plant and its further upgrades!

Page 35 1st Int. Conference on Frontiers in Diagnostic Technologies, Frascati, Italy, THANK YOU FOR YOUR ATTENTION!