Chapter 7: Diagnostics
TL;DR: In this paper, the authors describe the requirements for high reliability in the systems (diagnostics) that provide the measurements in the ITER environment, which is similar to those made on the present-day large tokamaks while the specification of the measurements will be more stringent.
Abstract: In order to support the operation of ITER and the planned experimental programme an extensive set of plasma and first wall measurements will be required. The number and type of required measurements will be similar to those made on the present-day large tokamaks while the specification of the measurements—time and spatial resolutions, etc—will in some cases be more stringent. Many of the measurements will be used in the real time control of the plasma driving a requirement for very high reliability in the systems (diagnostics) that provide the measurements. The implementation of diagnostic systems on ITER is a substantial challenge. Because of the harsh environment (high levels of neutron and gamma fluxes, neutron heating, particle bombardment) diagnostic system selection and design has to cope with a range of phenomena not previously encountered in diagnostic design. Extensive design and R&D is needed to prepare the systems. In some cases the environmental difficulties are so severe that new diagnostic techniques are required. a Author to whom any correspondence should be addressed.
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TL;DR: A broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices is given in this article.
Abstract: The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium?tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies.Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the ?sea? of Alfv?n eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).
222 citations
TL;DR: A spatially resolving high resolution x-ray crystal spectrometer has been built and installed on the Alcator C-Mod tokamak and can be inverted to infer profiles of impurity emissivity, velocity, and temperature.
Abstract: The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10,000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented.
123 citations
TL;DR: The design of the scintillator probe, the new technique used to analyze the data through spectrograms will be described, as well as the diagnosis prospects of this method for ITER.
Abstract: A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].
119 citations
TL;DR: In this article, the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra of highly-charged tungsten ions W54+ to W63+ obtained with an electron beam ion trap (EBIT) are presented.
Abstract: We report the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4–20 nm) of highly-charged tungsten ions W54+ to W63+ obtained with an electron beam ion trap (EBIT). Collisional-radiative modelling is used to identify strong electric-dipole and magnetic-dipole transitions in all ionization stages. These lines can be used for impurity transport studies and temperature diagnostics in fusion reactors, such as ITER. Identifications of prominent lines from several W ions are confirmed by the measurement of isoelectronic EUV spectra of Hf, Ta and Au. We also discuss the importance of charge-exchange recombination for the correct description of ionization balance in the EBIT plasma.
102 citations
TL;DR: In this article, the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4 nm to 20 nm) of highly-charged tungsten ions W$−54+}$ to W−63+$ obtained with an electron beam ion trap (EBIT).
Abstract: We report the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4 nm to 20 nm) of highly-charged tungsten ions W$^{54+}$ to W$^{63+}$ obtained with an electron beam ion trap (EBIT). Collisional-radiative modelling is used to identify strong electric-dipole and magnetic-dipole transitions in all ionization stages. These lines can be used for impurity transport studies and temperature diagnostics in fusion reactors, such as ITER. Identifications of prominent lines from several W ions were confirmed by measurement of isoelectronic EUV spectra of Hf, Ta, and Au. We also discuss the importance of charge exchange recombination for correct description of ionization balance in the EBIT plasma.
95 citations
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31 Mar 1983
TL;DR: In this article, the authors present a technique for shape measurements using holographic and speckle pattern interferometry techniques, based on the concept of correlation interferometrics.
Abstract: Preface to the first edition Preface to the second edition 1. Basic optical principles 2. Holographic interferometry 3. Speckle pattern interferometry 4. Electronic speckle pattern correlation interferometry 5. Holographic and speckle pattern interferometry techniques for shape measurements 6. Experimental design and technique 7. Applications Appendices References Index.
897 citations
01 Jan 1996
TL;DR: The ITER Project: The ITER Device R.R.C. Walker, L.M. de Kock, et al. as discussed by the authors proposed a Reflectometry System for ITER.
Abstract: The ITER Project: The ITER Device R.R. Parker, et al. The ITER Diagnostic Program K.M. Young, et al. Requirements for ITER Diagnostics A.E. Costley, et al. ITER Plasma Diagnostics Generic Access C.I. Walker, L. de Kock. Radiation Hardening of Diagnostic Components D.V. Orlinskij. Imitation of Fusion Reactor Environment Effects on the Inner Elements of Spectroscopical, mm and Submm Diagnostics V.S. Voitsenya, et al. Magnetic Diagnostics: Overview of Magnetic Diagnostics Planned for ITER L. de Kock, et al. Magnetic Equilibrium Reconstruction Techniques for Tokamak Reactors E. Lazzaro. Fast and Accurate Methods of Plasma Boundary Determination in ITER from External Magnetic Measurements Yu.K. Kuznetsov, I.V. Yasin. Reflectometry and ECE: Comparison of Different Reflectometry Techniques C. Laviron. ReflectometryApplications to ITER E.J. Doyle, et al. Reflectometry for ITER Density Profiles M. Manso, et al. Proposal of Reflectometry System for ITER V.A. Vershkov. ICRF Physics Measurements by Reflectometry A. Mase, et al. Interferometry, Polarimetry and Thomson Scattering: Advantages and Limitations of Microwave Diagnostics in ITER A.J.H. Donne, B.C. Schokker. Application of Interferometry and Faraday Rotation Techniques for Density Measurements on ITER R.T. Snider, et al. Development of Dual CO2 Laser Interferometer for Large Tokamak A. Nagashima, et al. Infrared Laser Diagnostics for ITER D.P. Hutchinson, et al. A Thomson Scattering Scheme for Obtaining Te and ne Profiles of the ITER Core Plasma C. Gowers, et al. Spectroscopy: Active Spectroscopic Diagnostics for ITER Utilizing Neutral Beams E.S. Marmar. Spectroscopy for Impurity Control in ITER N.J. Peacock, et al. Development of Luminescent Detectors for Hot Plasmas B. Zurro, et al. Multilayer Mirror Based Monitors for Impurity Controls in ITER S.P. Regan, et al. Feasibility of Quantitative Spectroscopy on ITER M.G. von Hellermann et al. Fusion Products: Fusion Product Measurements in DT Plasmas in TFTR L.C. Johnson, et al. DT Neutron Measurements and Experience on TFTR C.W. Barne, et al. A Neutron Camera for ITER: Conceptual Design F.B. Marcus, et al. Neutron Spectrometry for ITER J. Kallne, et al. Advanced Neutron Camera with Spectrometer Functions E. Traneus, et al. Divertor Diagnostics: Divertor Diagnosticsfor JET P.R. Thomas, et al. Spectroscopy of Divertor Plasmas R.C. Isler. Bolometry for Divertor Characterization and Control A.W. Leonard, et al. Bolometer for ITER R. Reichle, et al. Neutral Gas Diagnostic for ITER G. Haas, et al. Diagnostics of Other Fusion Experiments: Overview of W7X Diagnostics J.V. Hofmann, et al. Diagnostics for LHD J. Fujita, et al. The T15 Fusion Products Study: Plans and Diagnostics V.S. Zaveriaev, et al. 41 additional articles. Index.
253 citations
TL;DR: In this article, a Doppler reflectometry technique was used to measure Er fluctuations directly, and measurements of Geodesic acoustic modes (GAMs) and ZF properties in ohmic, L-mode and H-mode ASDEX Upgrade tokamak discharges were performed.
Abstract: Zonal flows (ZFs) and associated geodesic oscillations are turbulence-generated time-varying Er × BT rigid poloidal plasma flows with finite radial extent. They are of major interest for tokamak confinement since they are thought to moderate drift-wave turbulence and hence edge transport. However, detection of ZFs (believed to be driven by Reynolds stress) and Geodesic acoustic modes (GAMs) (linked with poloidal pressure asymmetries) is challenging since they appear predominantly as low frequency (few kilohertz) potential or radial electric field Er fluctuations. Presented here are measurements of GAM/ZF properties in ohmic, L-mode and H-mode ASDEX Upgrade tokamak discharges using a new Doppler reflectometry technique to measure Er fluctuations directly.
252 citations
TL;DR: In this article, the first tests of molybdenum mirrors were performed in the DIII-D divertor under deposition-dominated conditions, and two sets of mirrors recessed 2 cm below the divertor floor in the private flux region were exposed to a series of identical, lower-single-null, ELMing (featuring edge localized modes) H-mode discharges with detached plasma conditions in both divertor legs.
Abstract: Metallic mirrors will be used in ITER for optical diagnostics working in different spectral ranges. Their optical properties will change with time due to erosion, deposition, and particle implantation. First tests of molybdenum mirrors were performed in the DIII-D divertor under deposition-dominated conditions. Two sets of mirrors recessed 2cm below the divertor floor in the private flux region were exposed to a series of identical, lower-single-null, ELMing (featuring edge localized modes) H-mode discharges with detached plasma conditions in both divertor legs. The first set of mirrors was exposed at ambient temperature, while the second set was preheated to temperatures between 140 and 80°C. During the exposures mirrors in both sets were additionally heated by radiation from the plasma. The nonheated mirrors exhibited net carbon deposition at a rate of up to 3.7nm∕s and suffered a significant drop in reflectivity. Net carbon deposition rate on the preheated mirrors was a factor of 30–100 lower and their...
237 citations
TL;DR: Doppler reflectometry is characterized by a finite tilt angle of the probing microwave beam with respect to the normal onto the cutoff surface as mentioned in this paper, where the signal intensity contains information about the perturbation amplitude.
Abstract: Doppler reflectometry is characterized by a finite tilt angle of the probing microwave beam with respect to the normal onto the cutoff surface. According to the Bragg condition the diagnostic selects density perturbations with wave number K⊥ in the reflecting layer. From the Doppler shift of the returning microwave the propagation velocity of these perturbations v⊥ can be obtained directly. The signal intensity contains information about the perturbation amplitude. The diagnostic potential of Doppler reflectometry is demonstrated both numerically by the use of two-dimensional full-wave codes and experimentally by an antenna system with variable tilt angle installed at the W7-AS stellarator. During stationary plasma conditions the measured profile of the propagation velocity v⊥(r) is dominated by the E×B velocity of the plasma, which is obtained from passive spectroscopy. Transient states of the plasma can be followed with a temporal resolution of less than 50 µs. Thus, Doppler reflectometry allows us to investigate the interdependence of sheared flow and turbulence on that timescale.
218 citations