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This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain particle, momentum, and heat transport studies in a tokamak for the first time. Doppler tomography techniques have been extended to include propagation of statistical uncertainty due to photon noise, the effect of non-uniform instrumental broadening as well as flux surface variations in impurity density. These methods have been deployed as a suite of modeling and analysis tools, written in interactive data language (IDL) and designed for general use on tokamaks. Its application to the Alcator C-Mod XICS is discussed, along with novel spectral and spatial calibration techniques. Example ion temperature and radial electric field profiles from recent I-mode plasmas are shown, and the impact of poloidally asymmetric impurity density and natural line broadening is discussed in the context of the planned ITER x-ray crystal spectrometer. [ABSTRACT FROM AUTHOR]

X pinch plasmas produced from fine metal wires can reach near solid densities and temperatures of 1 keV or even more. Plasma conditions change on time scales as short as 5–10 ps as determined using an x-ray streak camera viewing a focusing crystal spectrograph or directly viewing the plasma through multiple filters on a single test. As a result, it is possible to determine plasma conditions from spectra with ∼10 ps time resolution. Experiments and theory are now coming together to give a consistent picture of the dynamics and kinetics of these high energy density plasmas with very high temporal and spatial precision. A set of diagnostic techniques used in experiments for spectrally, temporally, and spatially resolved measurements of X pinch plasmas is described. Results of plasma parameter determination from these measurements are presented. X ray backlighting of one x- pinch by another with ∼30 ps x-ray pulses enables the dynamics and kinetics to be correlated in time. [ABSTRACT FROM AUTHOR]

The pulse-height-analysis (PHA) system installed on the Joint European Torus (JET) measures the plasma soft x-ray emission (2–30 keV) with an energy resolution of 450 eV and a time resolution of 200 ms. This diagnostic includes three Si(Li) detectors, equipped with sets of remotely controlled apertures and filters, which view the plasma in the midhorizontal plane of the torus along a single tangential line of sight. Automatic analysis of the spectra yields the central electron temperature, the central concentrations of chlorine, chromium, and nickel, and Zeff. Simulations of the measured spectra using a radiation code provides the basis to construct a consistent picture of the soft x-ray emission in the central region of JET plasmas. [ABSTRACT FROM AUTHOR]

A prototype ultrasoft x-ray polychromator has been developed for local particle transport measurements in magnetic fusion devices using the Hα charge exchange emission from low-Z impurity pellets. High throughput together with few cm radial resolution in the plasma are achieved using a toroidally aligned grid collimator, while a few Å spectral bandpass together with strong background rejection are obtained using planar multilayer mirrors and foil filters. As high sensitivity detectors we use a new type of compact, efficient and high-gain multichannel plates. The prototype instrument has been evaluated in the laboratory and tested on the Large Helical Device in Japan. In addition to transport studies, this type of device is of interest for next step experiments, where high beam energy and strong attenuation will make visible charge exchange recombination spectroscopy difficult. [ABSTRACT FROM AUTHOR]

A least-squares fit analysis program is being developed for the study of spatially resolved x-ray spectra from tokamak plasmas. The program, written in interactive data language, can handle analysis of spectra from multiple sightlines through the plasma and compare the experimental data with a least-square fit of synthetic spectra, which are constructed from atomic modeling codes. The input parameters such as shot numbers, time groups, spatial range, spectral lines to fit and fitting parameters can be entered interactively through a graphical user interface or automatically via a script. The output consists of graphical presentations of the obtained spectral fits and fit parameter profiles as a function of time, including ion and electron temperature profiles, which are of particular interest. Output can also be sent to any open database connectivity compliant database. The features of the program are demonstrated with the analysis of the spectra of helium-like ArXVII, which were obtained with a new x-ray imaging crystal spectrometer. [ABSTRACT FROM AUTHOR]

Interest in x-ray absorption derives from soft x-ray transport studies to characterize laser-solid-interaction effects. The object of this work was to determine whether x-ray absorption features were measurable in laser-produced plasmas from solid targets. X-ray emission was made using high-atomic-number microsphere targets irradiated with a focused beam of the Pharos laser while the laser-solid-interaction plasmas were generated by a second beam in Al foil targets. High-resolution, spatially resolved x-ray spectra were collected with instrumentation and geometry similar to previous tracer-dot spectroscopy measurements of plasma profile parameters. Soft x-ray absorption lines, observed at different distances from the aluminum target surface, may be related to density gradients in the laser-generated plasmas. [ABSTRACT FROM AUTHOR]

An 800 × 800 Texas Instruments virtual phase charge-coupled device (CCD) was used to obtain pinhole images and x-ray spectra of laser-produced, solid target plasmas. With the CCD used in the single-photon counting mode, the spectrum in the energy range 2-10 keV was obtained without a dispersive element. Typical spectra reveal two distinct temperatures: a "cold" component of approximately 200 eV and "hot" component of approximately 5 keV. Also, multiline spectra comprising characteristic line emission (K[sub α], K[sub β]) from a multilayer target bombarded by β rays were recorded using a three-phase CCD. The results demonstrate the potential of CCDs as imaging spectrometers with application in space, laboratory, and fusion plasma research. [ABSTRACT FROM AUTHOR]