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Dielectric materials with high thermal conductivity (TC) can enable disruptive performance enhancement in the areas of electronics packaging, thermal management, energy storage, cabling, and heat sinks. There have been widespread global efforts over the past decade on developing novel nanocomposite dielectric materials. As a baseline, legacy polymers and epoxies used in the abovementioned applications have very low thermal conductivities ranging from 0.1–0.5 $\text{W}\cdot \text{m}^{-1} \cdot \text{K}^{-1}$ . Recent advances have led to the commercial availability of polymeric materials with thermal conductivities approaching 10 $\text{W}\cdot \text{m}^{-1} \cdot \text{K}^{-1}$ . Importantly, several fundamental studies report novel nanocomposites with thermal conductivities $>50\,\,\text{W}\cdot \text{m}^{-1} \cdot \text{K}^{-1}$ . This article summarizes progress in the development of such materials with a focus on developments that show promise for improved practical dielectrics. This review highlights that high TC alone is inadequate to characterize the suitability of any material for the above applications. Other thermal properties, such as thermal diffusivity, glass transition temperature, and the ratio of the in-plane to out-of-plane TC, are important to quantify the thermal performance of novel nanocomposites. In addition, characterization and understanding of mechanical properties (coefficient of thermal expansion (CTE), tensile strength and elastic modulus) and electrical properties (dielectric strength and dielectric permittivity) are critical for holistic multifunctional assessments of these materials. There are other parameters and properties that influence performance, life, and manufacturability, such as viscosity and moisture absorption. This study reviews all the above aspects of nanocomposite dielectric materials reported in the literature. More specifically, we analyze various filler-polymer combinations, and the influence of approaches to incorporate fillers in the polymer on the thermal, mechanical, and electrical properties. While the addition of fillers leads to huge enhancements in TC, the TC is highly anisotropic, with out-of-plane TC lower than in-plane TC by an order of magnitude. It is seen that most present-day materials are still inadequate for future applications due to their low glass transition temperatures; specific promising materials are highlighted. While the addition of fillers reduces the CTE, further reduction is needed to favorably improve the mechanical performance of these materials. While the electrical insulating properties of these composite materials are adequate, there is very little data reported on other electrical properties. In summary, while there is an understandable focus on enhancing the TC, other properties are underreported, and there is insufficient information to support the assessment of most novel materials for practical applications. Overall, this study summarizes the state-of-the-art dielectric nanocomposites and outlines directions for future research to bridge the gap between basic materials science and applications.

Machine learning (ML)-based predictive techniques are used in conjunction with a game-theoretic approach to predict the thermal behavior of a power electronics package, and study the relative influence of encapsulation material properties and thermal management techniques in influencing hotspot temperatures. Parametric steady-state and transient thermal simulations are conducted for a commercially available 1.2 kV/444 A silicon carbide (SiC) half-bridge module. An extensive databank of 2592 (steady-state) and 1200 (transient) data points generated via numerical simulations is used to train and evaluate the performance of three ML algorithms (random forest, support vector regression, and neural network) in modeling the thermal behavior. The parameter space includes the thermal conductivities of the encapsulant, baseplate, heat sink, and cooling conditions deployed at the sink and covers a variety of materials and cooling scenarios. Excellent prediction accuracies with R2 values > 99.5% are obtained for the algorithms. Shapley additive explanations (SHAP) dependence plots are used to quantify the relative impact of device and heat sink parameters on junction temperatures. We observe that while heatsink cooling conditions significantly influence the steady-state junction temperature, their contribution in determining the junction temperature in dynamic mode is diminished. Using ML-SHAP models, we quantify the impact of emerging polymeric nanocomposites (with high conductivities and diffusivities) on hotspot temperature reduction, with the device operating in steady-state and transient modes. Overall, this study highlights the attractiveness of ML-based approaches for thermal design, and provides a framework for setting targets for future encapsulation materials.

Wide band gap (WBG) semiconductors are delivering on the promise of higher power and energy density circuits. In doing so, they are also opening an opportunity for a new generation of dielectric materials. Researchers from the University of Texas at Austin organized a 1.5 day workshop on "Next-generation dielectric materials for microelectronics/electrical applications" at the Massachusetts Institute Technology on December 4–5, 2019 focusing on this emerging opportunity. The invitation-only workshop brought together the materials researchers with those attempting to improve power electronics (PE) packaging to compare information that would accelerate the field (Figure 1).

We highlight the predictive utility of machine learning (ML) techniques in estimating thermal performance benefits in power electronics modules, resulting from the use of high thermal conductivity polymers and thermal management techniques. The thermal performance of a commercial 1.2kV/444A SiC half-bridge module is quantified via high fidelity numerical simulations. Parametric simulations are conducted by considering the thermal conductivity of i) encapsulant (anisotropic), ii) baseplate and iii) heat sink as variable parameters, along with the coolant temperature and convection heat transfer coefficient. These simulations generate a data set of more than 2500 data points, which is used to train and evaluate the performance of machine learning algorithms to estimate the maximum junction temperature (T j ) of the package. Parameters are varied to represent a broad spectrum of possibilities ranging from high thermal conductivity polymer-based heat sinks to copper heat sinks; and air to two-phase liquid cooling technologies. The performance of three different statistical machine learning models is evaluated: polynomial regression, random forest, and support vector machines in predicting T j . While polynomial regression does not predict T j with a reasonable accuracy, random forest and support vector machines demonstrate excellent prediction accuracies w ith overall R2 of 99.6 and 99.98%, respectively. To estimate the relative contribution of the underlying thermal parameters, we use SHAP (Shapley Additive exPlanations) dependence plots in combination with random forest algorithm to identify parameters which strongly influence T j. We observe that the thermal conductivity of heat sink material and heat transfer coefficient have the maximum impact on T j reduction, whereas the thermal conductivity of the polymeric encapsulant has the least influence on T j . The presently used approach of simulations-based training of ML algorithms can be adapted for the thermal design and parameter optimization in other electronics packages.

Two blackbody sources permanently located within the international thermonuclear experimental reactor (ITER) diagnostic shield module at equatorial port 9 will operate in conjunction with two remotely retractable mirrors to generate and direct blackbody radiation to calibrate the radial and oblique views of the ITER electron cyclotron emission diagnostic. The main calibration requirements include a high-emissivity surface heated to 700 °C or higher, the ability to perform the calibration in high vacuum and in the presence of a magnetic field, and 5000-h operational lifetime over 20 years. Major constraints include a heater current limit of 40 A, no direct fluid cooling to mitigate failure risks, small size to avoid compromising neutron shielding, and adequate structural support to mitigate vibration loads. This paper describes the preliminary design of a hot calibration source supported by analysis and test results of a calibration source test prototype developed to address the calibration source requirements and its constraints.

Pumped storage hydro (PSH) based generation of electricity is a proven grid level storage technique. A new configuration i.e., adjustable speed PSH (AS-PSH) power plant is modeled and discussed in this paper. Hydrodynamic models are created using partial differential equations and the governor topology adopted from an existing, operational AS-PSH unit. Physics-based simulation of both hydrodynamics and power system dynamics has been studied individually in the past. This paper demonstrates a co-simulation of an AS-PSH unit between penstock hydrodynamics and power system events in a real-time environment. Co-simulation provides an insight into the dynamic and transient operation of AS-PSH connected to a bulk power system network. The two modes of AS-PSH operation presented in this paper are turbine and pump modes. A general philosophy of operating in turbine mode is prevalent in the field when the prices of electricity are high and in the pumping mode when prices are low. However, recently there is renewed interest in operating PSH to also provide ancillary services. A real-time co-simulation at sub-second regime of AS-PSH connected to the IEEE 14 bus test system is performed using digital real-time simulator and the results are discussed.

This paper describes the development of a prototype hot calibration source for the ITER-ECE diagnostic system. A resistive heating element encapsulated in an Inconel heating block was initially selected to heat a silicon carbide emitter to the required 700°C temperature. Radiative and direct contact heat transfer methods were considered and tested in a test prototype. The radiative heat transfer approach was selected and methods to improve the heater emissivity were investigated. Extended tests were conducted to verify long term heating performance, materials stability, and ITER vacuum compatibility. Design iterations guided by initial test results followed and alternative heater materials, heating elements, and heater design features were considered. Initial design, analysis, and test results are presented. Subsequent efforts to meet the full requirements of the hot calibration source are also presented.

Rapid miniaturization alongwith increasing heat loads in power electronics devices like insulated-gate bipolar transistors (IGBTs) have necessitated the need for advanced thermal management technologies in the packaging of these devices. This study quantifies the benefits of key advanced thermal management solutions for packaging of power electronics packages. Thermal resistance network modeling is used to estimate the maximum heat flux that can be dissipated by an IGBT package, while maintaining the junction temperature below 125 °C and 200 °C for silicon and silicon carbide (wide bandgap material) devices, respectively. While the model is completely analytical, it does address important complexities associated with heat flow in packages via the use of a sub-model to account for thermal spreading. The advanced cooling technologies evaluated in this study include the use of high thermal conductivity polymer heat sinks, double-sided heat sinking of packages, liquid cooling (single and two-phase), jet impingement and spray cooling. Additionally, combinations of these cooling technologies are evaluated as well. The heat dissipation achievable from these technologies is compared with that from an air cooled copper heat sink (baseline). The results of this study provide insights and a starting point for selecting thermal management technologies (or combinations) based on the heat dissipation requirements of power electronics packages.

Emerging high power electric weapons and sensors create challenges for future naval power systems. To address these large transient loads, energy storage systems must have high energy and power density and be capable of high slew rates — rapidly transitioning from supplying to absorbing energy. These energy storage systems have been conceived to support specialized mission loads within the ship's electrical power system. This paper presents two rotating machine concepts that combine inertial energy storage and transient power capability to mitigate the impact of these transient loads on the power system. These machines are key elements of modular, multi-mode power supplies that can be tailored to range of naval power system applications.

Many future U.S. Navy ships will employ all-electric propulsion systems instead of mechanical drives. To help optimize performance of these systems, studies are under way at The University of Texas at Austin Center for Electromechanics (UT-CEM) to minimize the size of power generation components. These studies focus on increasing the power density of directly coupled gas turbines and generators (gen-sets). The approach adopted in this paper uses scaling laws of gas turbines and synchronous electrical generators to examine the possibility of increasing power density by operating at higher shaft speeds. Included is consideration of inlet and exhaust turbine ducts and issues involving power electronics. Study results indicate that if inlet and exhaust duct volumes are neglected, the power density of directly coupled gas turbine-generator sets can be significantly improved by scaling to higher operating speeds. However, the advantages of scaling to higher speeds are largely negated when duct volumes typically encountered on modern ships are included. This suggests locating power generation equipment near the ambient terminus of inlet and exhaust ducts, so that duct lengths are minimized and fully exploiting the power density advantages of scaling to higher shaft speeds becomes possible.

The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed and conducted component test/development for a flywheel energy storage system for pulsed loads and mobility load leveling in a tactical vehicle. Performance goals of this machine dictate that the stator windings will see continuous voltages of 6.7 kV and spikes to 10 kV. To manage the thermal loads produced by the intermittent 5 MW output pulses, and continuous 350 kW duty, the generator is cooled by oil at a maximum temperature of 90/spl deg/C. UT-CEM designed and developed a novel insulation system and dual coolant passage arrays for the stator. Design performance was verified in laboratory prototype testing. This paper summarizes design goals, analysis, and mockup testing of the motor-generator stator.

Advanced energy storage systems for electric guns and other pulsed weapons on combat vehicles present significant challenges for rotor bearing design, Active magnetic bearings (AMBs) present one emerging bearing option with major advantages in terms of lifetime and rotational speed, and also favorably integrate into high-speed flywheel systems. The Department of Defense Combat Hybrid Power Systems (CHPS) program serves as a case study for magnetic bearing applications on combat vehicles. The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed active magnetic bearing actuators for use in a 5 MW flywheel alternator with a 318 kg (700 lb), 20000 rpm rotor. To minimize CHPS flywheel size and mass, a topology was chosen in which the rotating portion of the flywheel is located outside the stationary components. Accordingly, magnetic bearing actuators are required which share this configuration. Because of inherent low loss and nearly linear force characteristics, UT-CEM has designed and analyzed permanent magnet bias bearing actuators for this application. To verify actuator performance, a nonrotating bearing test fixture was designed and built which permits measurement of static and dynamic force. An AMB control system was designed to provide robust, efficient magnetic levitation of the CHPS rotor over a wide range of operating speeds and disturbance inputs, while minimizing the occurrence of backup bearing touchdowns. This paper discusses bearing system requirements, actuator and controller design, and predicted performance; it also compares theoretical vs. measured actuator characteristics.

Reduced-order average-value models form the basis of a computationally efficient approach for studying shipboard power systems. As a result of neglecting fast states, this approach generally involves solving a set of differential algebraic equations. Although the reduced-order average-value modeling approach has been well studied in the literature, as simulation languages evolve the most programmatic approach to addressing the non-linear algebraic portion of the model changes as well. In this work, a number of approaches for implementing reduced-order average-value models of a small power system are compared.

Considerable progress has been made on the design of the ITER electron cyclotron emission (ECE) diagnostic over the past two years. Radial and oblique views are still included in the design in order to measure distortions in the electron momentum distribution, but the oblique view has been redirected to reduce stray millimeter radiation from the electron cyclotron heating system. A major challenge has been designing the 1000 K calibration sources and remotely activated mirrors located in the ECE diagnostic shield module (DSM) in the equatorial port plug #09. These critical systems are being modeled and prototypes are being developed. Providing adequate neutron shielding in the DSM while allowing sufficient space for optical components is also a significant challenge. Four 45-meter long low-loss transmission lines transport the 70–1000 GHz ECE from the DSM to the ECE instrumentation room. Prototype transmission lines are being tested, as are the polarization splitter modules that separate O-mode and X-mode polarized ECE. A highly integrated prototype 200–300 GHz radiometer is being tested on the DIII-D tokamak in the USA. Design activities also include integration of ECE signals into the ITER plasma control system and determining the hardware and software architecture needed to control and calibrate the ECE instruments.

Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct view of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.

The response of a tokamak discharge to a sharp drop in edge temperature differs significantly from that expected from typical local transport models in several important respects. Laser ablation of carbon induces large (ΔT/T≤70%), rapid (

To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.

A model of an autonomous power system that generates and distributes power at 240 Hz has been developed. This high-frequency ac power system (HFAC) includes several gas turbine-generator units, two propulsion power trains, several power distribution and conversion units, a super-capacitor energy storage module, a high-power pulse load, and multiple service loads. Four case studies are considered. These are: partial loss of generation, application of a large step load, power restoration to a vital load, and operation of energy storage. Preliminary analysis shows that the power system remains under control during the four events. Some benefits of the HFAC architecture are highlighted first and analysis results of the case studies follow.

Effective interruption of load currents under both normal and fault conditions presents major challenges in medium-voltage dc distribution systems. In a highly-integrated dc power system, the preponderance of power converters connecting several loads with power ranging from (W) to (MW) levels rises additional concerns about the effects of a dc fault on other loads connected to the same bus or adjacent buses. Equally critical are the interactions between these power converters during the fault isolation and clearance process. In order to address some of these issues, a basic model has been constructed to study the behavior and effects of dc faults in an MVDC power system for an all-electric ship. Results of the analysis are presented.

Profiles of the ion thermal diffusion coefficient χi have been determined experimentally for several TEXT plasma discharges. In the confinement region, the inferred values of χi are larger than the values predicted by neoclassical theory by a factor of two to six. No evidence of a reduction of thermal losses through the ion channel is found after injection of hydrogen pellets. The inferred electron thermal conductivities are larger than the ion thermal conductivities by an average factor of three. The anomaly in χi is compared with transport coefficients predicted by different models that describe the ηi instability.

Heavy ion beam probes (HIBPs) have proven to be a unique tool for measuring fluctuations and particle transport in tokamaks. They have been used to measure fluctuations in density, electric potential, and magnetic vector potential. The density and potential fluctuation measurements have determined the particle flux due to electrostatic turbulence in the TEXT and ISX‐B tokamaks. In these measurements, the frequency spectra (0–500 kHz) of the phase between density and potential, the wave numbers of the fluctuations, and the fluctuation level are obtained. Three topics are discussed in this paper. We present measurements of magnetic fluctuations during MHD activity using the TEXT HIBP. Analysis of these measurements indicates that the diagnostic is primarily sensitive to the local value of Aφ in the sample volume unless the local Aφ is small. In addition, we discuss instrumental effects associated with wave number measurements. We will discuss the effects of sample volume size on the wave number measurements...

Prime power generation on board all-electric ships presents several options that affect fuel consumption, power density, operational effectiveness, and survivability. A study that aims at understanding the effects of some of these options has been conducted and results are reported in this paper. It is found that direct coupling of gas turbines to permanent magnet generators reduces system mass and volume significantly as compared to electric power generation systems installed on present-day navy ships. Furthermore, it is found that a significant benefit this topology brings is a reduction in gas turbine air duct volume if the compact gen-set units are relocated on or near the ship's upper decks. In addition, a combinatory analysis revealed that the choice of the number of generating units and their respective power levels has a significant influence on overall efficiency.

The article of record as published may be found at http://dx.doi.org/10.1109/TMAG.2006.887676 Part of the technical versatility of future all-electric ships is the potential ability to share large amounts of power among a variety of high-power loads. To help evaluate this potential and to provide information to help guide technology selection, a physics-based model of a power train for an electric ship has been developed and implemented on three modeling platforms. Using this model, three different investigations have been carried out to explore aspects of the behavior of a rotating machine power source for a shipboard rail launcher. These were: 1) influence of rapid charging of the rotating machine system on the ship power system; 2) use of the stored energy in the rotating machines to improve ship power quality; and 3) use of the stored energy in the rotating machines to power a pulsed free-electron laser. Each study highlighted different integration opportunities and challenges. The first showed that, because the charging of the rail launchers was through 5-MW motors, there could be a voltage sag for a few cycles, but this could easily be managed so that the sag could be reduced to an inconsequential level. The second study showed that, with appropriate power electronics, the stored energy in the rail launcher power supply can be used to correct power quality problems introduced by other ship systems. Finally, the stored energy in the launcher power supply can be used to fire a free electron laser for ship defense. This feature opens the possibility of routine operation of the entire ship at highest efficiency, i.e., with the smallest number of gas turbines operating near full power, while providing stored energy needed for ship defense. This work was supported by the Office of Naval Research.

The Center for Electromechanics (CEM) at the University of Texas is engaged in the development of a comprehensive power system model in order to address several challenging issues facing the development of a viable and effective integrated power system architecture for future naval platforms. The power system under consideration reflects the notional DD power system architecture and is developed in the Matlab/Simulink environment. System components such as motors and generators are modeled using parameters based on actual machine design and analysis work performed at CEM. Simulation results of models including permanent-magnet propulsion motors and generators with simple reconfiguration scenarios simulating loss and recovery of power to propulsion and vital loads are presented.

In this study, the baseline design for the ITER electron cyclotron emission (ECE) diagnostic has entered the detailed preliminary design phase. Two plasma views are planned, a radial view and an oblique view that is sensitive to distortions in the electron momentum distribution near the average thermal momentum. Both views provide high spatial resolution electron temperature profiles when the momentum distribution remains Maxwellian. The ECE diagnostic system consists of the front-end optics, including two 1000 K calibration sources, in equatorial port plug EP9, the 70-1000 GHz transmission system from the front-end to the diagnostics hall, and the ECE instrumentation in the diagnostics hall. The baseline ECE instrumentation will include two Michelson interferometers that can simultaneously measure ordinary and extraordinary mode ECE from 70 to 1000 GHz, and two heterodyne radiometer systems, covering 122-230 GHz and 244-355 GHz. Significant design challenges include 1) developing highly-reliable 1000 K calibration sources and the associated shutters/mirrors, 2) providing compliant couplings between the front-end optics and the polarization splitter box that accommodate displacements of the vacuum vessel during plasma operations and bake out, 3) protecting components from damage due to stray ECH radiation and other intense millimeter wave emission and 4) providing the low-loss broadbandmore » transmission system.« less

Summary form only given. Analysis of nonstationary plasma fluctuation data has been a long-time challenge for the plasma diagnostic community. Many fluctuation diagnostic tools are Fourier-based such as power spectra and S(k,/spl omega/), to mention just a few. These diagnostic tools are particularly useful in analyzing stationary plasma fluctuation data. However, they have limited utility, if any at all, when the fluctuations are statistically nonstationary. For this reason, in this paper we present and apply wavelet transforms as a new diagnostic tool to analyze nonstationary plasma fluctuation data. Unlike the Fourier transform, which represents a given signal globally without temporal resolution, the wavelet transform provides local representation of the given signal in the time-scale domain. Compared to the so-called short-time Fourier transform, the wavelet transform has multiresolution capabilities. These capabilities enable the wavelet transform to analyze a given nonstationary signal at various time-scale resolutions. The fundamental concepts and multiresolution properties of wavelet transforms, along with a brief comparison with the short-time Fourier transform, are presented in this paper. The selection of a prototype wavelet or a mother wavelet is also discussed. The efficacy of the wavelet approach is demonstrated by analyzing transient broadband electrostatic potential fluctuations inside the inversion radius of sawtoothing TEXT-U plasmas during electron cyclotron resonance heating.

Summary form only given, as follows. The 2 MeV HIBP on TEXT-Upgrade has been used to measure the plasma potential for a variety of discharge conditions. Small scale, multiple point measurements throughout a cross section of the plasma give variations in electric field with a resolution of better than 10 V/cm. Scan lines through the plasma produce a potential profile along a radial path from plasma center to edge. Changes in electric field and potential are monitored during impurity injection and with 500 kW of ECH heating. Fluctuations in plasma potential have been observed deep within the plasma with 40 V rms sensitivity.

We use a diagnostic neutral beam, a scanning neutral particle energy analyzer, and Hα measurements to estimate the neutral density profile from the edge to the center of the TEXT tokamak. The diagnostic neutral beam provides a spatially localized density of neutrals. The plasma neutral density is measured from the ratio of the signals seen with and without the beam. The Hα measurements provide neutral profiles in the edge region and the global particle confinement time τp. The shapes of the observed neutral energy spectra put a lower bound on the central neutral density. Results are compared with estimates of NUT and general agreement is found. Error estimates are given.

A finite but small injection of carbon into the TEXT tokamak edge induces significant temperature perturbations throughout the plasma. Large, rapid temperature decreases are observed in the outer third, while temperatures in the inner third promptly begin to rise. The effects cannot be reproduced with transport coefficients that are functions only of local thermodynamic variables. A large increase in ${\ensuremath{\chi}}_{e}$ must occur within 100 \ensuremath{\mu}s in the outer region, and ${\ensuremath{\chi}}_{e}$ must simultaneously begin to decrease in the interior. Increases in local density fluctuation levels coincide with the increase in ${\ensuremath{\chi}}_{e}$.

The ITER ECE diagnostic has recently been through a conceptual design review for the entire system including front end optics, transmission line, and back-end instruments. The basic design of two viewing lines, each with a single ellipsoidal mirror focussing into the plasma near the midplane of the typical operating scenarios is agreed upon. The location and design of the hot calibration source and the design of the shutter that directs its radiation to the transmission line are issues that need further investigation. In light of recent measurements and discussion, the design of the broadband transmission line is being revisited and new options contemplated. For the instruments, current systems for millimeter wave radiometers and broad-band spectrometers will be adequate for ITER, but the option for employing new state-of-the-art techniques will be left open.

Electron temperature measurements and electron thermal transport inferences will be critical to the nonactive and deuterium phases of ITER operation and will take on added importance during the alpha heating phase. The diagnostic must meet stringent criteria on spatial coverage and spatial resolution during full field operation. During the early phases of operation, it must operate equally well at half field. The key to the diagnostic is the front end design. It consists of a quasioptical antenna and a pair of calibration sources. The radial resolution of the diagnostic is less than 0.06 m. The spatial coverage extends at least from the core to the separatrix with first harmonic O-mode being used for the core and second harmonic X-mode being used for the pedestal. The instrumentation used for the core measurement at full field can be used for detection at half field by changing the detected polarization. Intermediate fields are accessible. The electron cyclotron emission systems require in situ calibration, which is provided by a novel hot calibration source. The critical component for the hot calibration source, the emissive surface, has been successfully tested. A prototype hot calibration source has been designed, making use of extensive thermal and mechanical modeling.

Summary form only given. A 2-MeV heavy ion beam probe with two primary beam lines and two secondary beam detectors, presently under construction, will be used to measure the space potential and to determine the fluctuation characteristics in the TEXT-Upgrade diverted plasma during the anticipated H-mode operations. A Proca-Green-type electrostatic energy analyzer requires that 400 kV be held on a large (150-cmt40-cm) plate across a 20-cm vacuum gap. Such a high voltage on a large electrode may be difficult to maintain for an adequate period of time. Besides being large, the high voltage plate is designed so that it is 90% transparent to UV radiation which can be detrimental to the measurements. This requirement may cause additional problems when high voltage is applied to the electrode. In order to identify the problem that might arise in this particular high-voltage environment. an electrode structure identical to that of the actual analyzer is being built for testing purposes. If the high-voltage tests indicate that the Proca-Green analyzer is not feasible for analyzing a 2-MeV beam, a different kind of analyzer which requires a lower voltage will be used

Light impurity density profiles following hydrogen gas puff and hydrogen pellet fuelling have been obtained via charge exchange recombination spectroscopy on TEXT. After hydrogen pellet fuelling, C+6 and O+8 profiles are more strongly peaked on axis than the electron density profile. In contrast, light impurity profiles measured during sawtoothing high density gas puff fuelled discharges peak to a lesser degree relative to the electrons, with lower central densities than in the pellet case. The shapes of the peaked pellet impurity profiles are well described by neoclassical theory. The measured transport coefficients are larger than neoclassical values. The inferred inward convective velocity is consistent with values measured by impurity injection during sawtoothing discharges, but the diffusion coefficient is an order of magnitude lower than that obtained with impurity injection.

Neutral density profiles are measured in the outer third of the plasma of the TEXT tokamak in conjunction with ion temperature measurements using the far line wings of a Hα profile. The advantage of this technique is that it does not require a radial inversion of the data to obtain a measure of the local neutral density. The ion temperature profiles are compared with the results from a neutral particle analyzer, and the neutral profiles with the results of a numerical code which solves a system of coupled linear equations describing particle transport from a neutral source.