Engineering the Alcator C-Mod MSE diagnostic: Solutions to reactor-relevant diagnostic challenges
Deploying precise optical diagnostics in harsh reactor environments poses significant engineering challenges including limited access, large forces, time-varying systematic errors, reflections, low signal-to-background levels and a need for in-situ calibration. Fielding a polarization-based Motional Stark Effect (MSE) diagnostic on Alcator C-Mod has proven to be difficult due to similar challenges, which has led to the development of solutions that enable polarization angle measurements with an accuracy of 0.2 degrees.
A motional stark effect instrument to measure q(R) on the C-mod tokamak
A motional Stark effect (MSE) instrument to measure q(r) using the Torus Experiment for Technology (TEXT) neutral beam on the Alcator C-Mod tokamak has been designed and installed. The neutral beam is on the midplane, aimed radially, and designed to operate in hydrogen at 50 keV. The MSE optics view the outer half of the plasma −0.3<(R−R0)/a<1.05. This geometry results in a spatial resolution of 1 (edge)–3 (center) cm from a beam apertured horizontally to 2 cm. Estimates of the signal levels indicate for Hα that photoelectron statistical errors in the measurement of Bθ/Bφ can be less than 0.2% for ne0<2.0×1014 cm−3 similar to other MSE instruments. The collection optics reside within the vacuum chamber reflecting and imaging the neutral beam through a vacuum window in the neutral beam port. The optics are designed so that beam emission spectroscopy can be carried out simultaneously with MSE measurements. Optical signals are transmitted to remote detectors by fiber optics. Low Verdet glass and dielectric m...
Physical Processes in Inorganic Scintillators
BASIC PRINCIPLES AND PROCESSES Physical Mechanism of Scintillation Creation of Electron Hole Pairs Excitation and Emission of Luminescence Centers Scintillation Materials Halides Oxides and Oxide Systems Chalcogenides Glasses Interaction of Ionizing Radiation with Scintillators High Energy Photons Charged Particles Neutral Particles General Characteristics of Inorganic Scintillators Light Yield Duration of Scintillation Pulse Afterglow Temperature Response Optical Properties Radiation Hardness Density Emission Spectra Mechanical and Chemical Properties Physical Parameters Cost Consideration Scintillator Requirements in Various Applications High Energy Physics Intermediate Energy Physics Positron Emission Tomography Gamma Spectroscopy Energy Resolution Intrinsic Scintillator Resolution Nonproportional Response Time Resolution Low Energy Quanta and Electrons CONVERSION OF ELECTRONIC EXCITATIONS IN SOLIDS Charge Carrier Behaviors Delta Rays Secondaries Excitation of Luminescence Centers Effect of Ionization Density Energy Losses Simple Phenomenological Model Plasmon Model Polaron Model Scintillation Yield Spectra Vacuum Ultraviolet Region Ultrasoft X-Rays X-Rays Gamma Rays Heavy Ionizing Particles INTRINSIC LUMINESCENCE OF INORGANIC SCINTILLATORS Excitonic Luminescence Alkali Halide Crystals Alkaline-Earth Fluorides Ternary Halide Compounds Excitonic-Like Luminescence Cesium Iodide Tungstate and Molybdate Phosphors Core-to-Valence Transitions First Evidence for Radiative Core-to-Valence Transitions Excitation Spectra Emission Spectra Experiment Theory Luminescence Kinetics Experimental Theoretical Investigations Temperature Dependence of Luminescence Parameters Conditions of Detection Prospects for Research EXTRINSIC LUMINESCENCE OF INORGANIC SCINTILLATORS Thallium-Activated Halide Scintillators Crystals with NaCl-Type Structure Crystals with CsCl-Type Structure Other Thallium-Based and Thallium-Doped Crystals Crystals Containing Other ns2 Ions Bismuth Germanate (BGO) Sodium-Activated Cesium Iodide Rare-Earth-Activated Crystals General Considerations Europium-Activated Crystals Cerium-Activated Compounds Preliminary Comments LaF3-CeF3 Systems Cerium Chloride Barium Fluoride Gadolinium-Containing Crystals Lu- and Y-Containing Crystals Nd- and Pr-Activated Crystals DEFECT FORMATION BY IONIZING RADIATION Effect on Scintillator Characteristics Mechanisms of Defect Formation Efficiency of Defect Production Geometrical Factor Separation between F and H Centers Temperature Dependence of Production Efficiency Role of Halogen Ion Impurities Effect of Cation Impurities Formation Time of F-H Pairs Closing Comments References Index