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New liquid scintillators for fiber-optic applications

Description: New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented.
Date: January 1, 1981
Creator: Lutz, S. S.; Franks, L. A.; Flournoy, J. M. & Lyons, P. B.
Partner: UNT Libraries Government Documents Department

Using spectral line profiles as a diagnostic of the plasma electron density

Description: A description of a simple interactive fitting procedure is given which uses line profiles calculated for highly stripped ions, i.e., hydrogenic, helium-like and lithium-like species. Information on the calculation of these profiles is provided. The experimental data is read from disk, so any appropriately formatted data can be referenced.
Date: August 1, 1981
Creator: Lee, R.W. & Matthews, D.L.
Partner: UNT Libraries Government Documents Department

Pulsed versus direct current calibration of a proximity focused x-ray streak camera

Description: The absolute sensitivity of a proximity focused x-ray streak tube was measured with dc Henke tube x-ray line sources. Calibration covered the photon energy range from 0.930 to 8.05 keV at five points. These data were compared to a model of sensitivity based on photocathode response and matched the model well on a relative scale. A pulsed comparison was performed using a laser-plasma x-ray source. The calculated camera sensitivity was folded with the measured spectrum and compared to measured film exposures. The predicted exposures were 6.5 times less than the measured exposures, verifying concerns that the proximity focused tube response is nonlinear with flux at low, dc flux levels. Results of dc recalibrations that varied flux levels determined the extent of this phenomenon.
Date: February 1, 1981
Creator: Rockett, P.D. & McGurn, J.S.
Partner: UNT Libraries Government Documents Department

Techniques for the reconstruction of two-dimensional images from projections

Description: Several plasma diagnostics techniques measure the line integrals of quantities such as densities and optical, ultraviolet, and X-ray emission. Some approaches for reconstructing the local quantities from their line integrals, based on methods utilized in computerized tomography, electron microscopy, holographic interferometry, and radio astromony, are derived and presented. Results for the special cases with source functions posessing helical symmetry--ranging from DNA to MHD--are emphasized.
Date: August 1, 1978
Creator: Sauthoff, N.R. & Von Goeler, S.
Partner: UNT Libraries Government Documents Department

Scrapeoff layer studies with an instrumented limiter

Description: An instrumented limiter was used as a diagnostic to measure energy deposition and power fluxes in the scrapeoff layer. The limiter consisted of an array of 12 tiles, each equipped with a thermocouple. This arrangement represented a calorimeter array that yielded the total limiter energy and decay length of the power flux in the scrapeoff layer. Energy deposition and decay lengths are discussed for various plasma parameters.
Date: January 1, 1986
Creator: Mioduszewski, P.; Edmonds, P.H.; Emerson, L.C. & Simpkins, J.E.
Partner: UNT Libraries Government Documents Department

PDX infrared TV camera system

Description: An infrared TV camera system has been developed for use on PDX. This system is capable of measuring the temporal and spatial energy deposition on the limiters and divertor neutralizer plates; time resolutions of 1 ms are achievable. The system has been used to measure the energy deposition on the PDX neutralizer plates and the temperature jump of limiter surfaces during a pulse. The energy scrapeoff layer is found to have characteristic dimensions of the order of a cm. The measurement of profiles is very sensitive to variations in the thermal emissivity of the surfaces.
Date: August 1, 1981
Creator: Jacobsen, R.A.
Partner: UNT Libraries Government Documents Department

Pulse pile-up effects

Description: The energy spectrum containing the effects of all orders of pulse pileup is predicted for an idealized x-ray pulse-height-analysis system measuring randomly occurring events. Two simplifying assumptions used are first a fixed pulse resolution time and second that the measured energy of piled-up pulses is the algebraic sum of the energy associated with each pulse.
Date: May 1, 1983
Creator: Tenney, F.H.
Partner: UNT Libraries Government Documents Department

Dielectronic satellite spectrum of helium-like iron (Fe XXV)

Description: Dielectronic satellite spectra of Fe XXV near 1.8500 A have been observed from PLT (Princeton Large Torus) tokamak plasma discharges for electron temperatures in the range from 1.5 to 3 keV and an electron density of 2 x 10/sup 13/ cm/sup -3/. The electron temperature was independently determined from the electron cyclotron radiation emitted by the plasma. The quality of the spectra allows a detailed comparison with theoretical prediction, which is of importance in view of diagnostic applications.
Date: April 1, 1979
Creator: Bitter, M.; Hill, K.W.; Sauthoff, N.R.; Efthimion, P.C.; Meservey, E.; Roney, W. et al.
Partner: UNT Libraries Government Documents Department

Low-energy x-ray instrumentation for SHIVA. Final report

Description: This document reports the results of a study by Lockheed Palo Alto Research Laboratory on the optimization of low-energy x-ray diagnostic instrument for the SHIVA laser facility at the Lawrence Livermore Laboratory. Preliminary outlines for the basic system and several components are presented, experimental considerations and techniques are recommended, and further studies are suggested.
Date: June 1, 1978
Partner: UNT Libraries Government Documents Department

Wide spectrum microwave pulse measurement

Description: Various techniques are postulated as diagnostics for wide band microwave pulses. The diagnostics include determinations of both the instantaneous amplitude and the frequency content of one-shot pulses. 6 refs., 11 figs. (WRF)
Date: January 1, 1986
Creator: King, R.J.
Partner: UNT Libraries Government Documents Department

Streaked spectrometry using multilayer x-ray-interference mirrors to investigate energy transport in laser-plasma applications

Description: Transport of energy in laser-produced plasmas is scrutinized by devising spectrally and temporally identifiable characteristics in the x-ray emission history which identify the heat-front position at various times in the heating process. Measurements of the relative turn-on times of these characteristics show the rate of energy transport between various points. These measurements can in turn constrain models of energy transport phenomena. We are time-resolving spectrally distinguishable subkilovolt x-ray emissions from different layers of a disk target to examine the transport rate of energy into the target. A similar technique is used to measure the lateral expansion rate of the plasma spot. A soft x-ray streak camera with 15-psec temporal resolution is used to make the temporal measurements. Spectral discrimination of the incident signal is provided by multilayer x-ray interference mirrors.
Date: August 1, 1981
Creator: Stradling, G.L.; Barbee, T.W. Jr.; Henke, B.L.; Campbell, E.M. & Mead, W.C.
Partner: UNT Libraries Government Documents Department

Design of neutron streak camera for fusion diagnostics

Description: In laser fusion, such as with the NOVA under construction at the Lawrence Livermore National Laboratory, the D-T reaction is expected to be complete within 100 ps. It is important to measure the time-dependence of the neutron flux from the fusion target. We describe the design of a new neutron detector of 20 ps resolving time that can be used to study the history of fusion burn.
Date: June 16, 1981
Creator: Wang, C.L.; Kalibjian, R. & Singh, M.S.
Partner: UNT Libraries Government Documents Department

Low-energy x-ray and electron physics and applications to diagnostics development for laser-produced plasma research. Final report, April 30, 1980-April 29, 1981

Description: This final report describes a collaborative extension of an ongoing research program in low-energy x-ray and electron physics into particular areas of immediate need for the diagnostics of plasmas as involved in laser-produced fusion research. It has been for the continued support for one year of a post-doctoral research associate and for three student research assistants who have been applied to the following specific efforts: (1) the continuation of our research on the absolute characterization of x-ray photocathode systems for the 0.1 to 10 keV photon energy region. The research results were applied collaboratively to the design, construction and calibration of photocathodes for time-resolved detection with the XRD and the streak and framing cameras; (2) the design, construction and absolute calibration of optimized, bolt-on spectrographs for the absolute measurement of laser-produced plasma spectra.
Date: August 1, 1981
Creator: Henke, B.L.
Partner: UNT Libraries Government Documents Department

Pinhole imaging of laser-produced thermonuclear alpha particles

Description: Results of pinhole images of thermonuclear alpha particles generated by exploding pusher targets in the Argus laser facility are reviewed. Recorded images indicate that the reactions occur within a 25 to 30 micron region with twelve micron resolution for ten micron pinholes and thirty micron resolution for twenty-five micron pinholes. These results are in good agreement with LASNEX computer predictions and are confirmed by Zone Plate imaging of the burn conducted by Natale M. Ceglio at LLL. Planned three-dimensional imaging of the burning D-T gas in the Shiva laser facility using seven micron pinholes is discussed. Higher yields (approximately 5 x 10/sup 10/ reactions) and three orthogonal images of the burn will provide a data base for analysis using an Algebraic Reconstruction Technique to provide a higher resolution (9 micron), three-dimensional view of the burn.
Date: November 1, 1977
Creator: Brooks, K.M.; Ceglio, N.M.; Slivinsky, V.W.; Ahlstrom, H.G.; Storm, E.K.; Kornblum, H.N. et al.
Partner: UNT Libraries Government Documents Department

Time-resolved x-ray diagnostics

Description: Techniques for time-resolved x-ray diagnostics will be reviewed with emphasis on systems utilizing x-ray diodes or scintillators. System design concerns for high-bandwidth (> 1 GHz) diagnostics will be emphasized. The limitations of a coaxial cable system and a technique for equalizing to improve bandwidth of such a system will be reviewed. Characteristics of new multi-GHz amplifiers will be presented. An example of a complete operational system on the Los Alamos Helios laser will be presented which has a bandwidth near 3 GHz over 38 m of coax. The system includes the cable, an amplifier, an oscilloscope, and a digital camera readout.
Date: January 1, 1981
Creator: Lyons, P.B.
Partner: UNT Libraries Government Documents Department

Line shapes for some specific transitions in Hydrogenic, Lithium-like, and Helium-like ions

Description: A set of computer codes have been developed to produce spectral line shapes of highly stripped ions for a number of transitions in Hydrogenic, Helium-like and Lithium-like species. The choice of the transitions has been dictated largely by the laser compression experiments. The transitions of Hydrogenic species are: Lyman ..cap alpha..; Lyman ..beta..; Lyman ..gamma..; Lyman delta; Balmer ..cap alpha..; and Balmer ..beta... The transitions of Helium-like species are: 1s/sup 2/(/sup 1/S/sub 0/)-1s2p(/sup 1/P); 1s/sup 2/(/sup 1/S/sub 0/)-1s3p(/sup 1/P); 1s/sup 2/(/sup 1/S/sub 0/)-1s4p(/sup 1/P) and the associated dipole-forbidden components. The transitions of Lithium-like species are the entire n = 2 to n = 3 and n = 4 complexes.
Date: December 29, 1980
Creator: Lee, R.W.
Partner: UNT Libraries Government Documents Department

Diagnostic for measurement of radiated energy from a toroidal plasma

Description: Impurity line radiation can be a serious loss mechanism for a plasma. A diagnostic was needed for measuring the radiation loss on ZT-S, a toroidal reverse field pinch, so that the loss could be compared with total energy loss from the plasma. In the techniques described here the total number of photons emitted from the plasma and the average photon energy are found. The number of incident photons is measured by a calibrated detector that observes a limited region of plasma. By measuring the emission from two different chords and using the optical properties of the system, one can obtain the total number of photons emitted from the plasma per unit time and per unit length. To obtain the average photon energy one must know the relative sensitivity of both the spectrograph and film vs wavelength. Then the time-integrated radiated power is compared with the total energy loss from the plasma.
Date: June 1, 1978
Creator: Howell, R.B. & Karr, H.J.
Partner: UNT Libraries Government Documents Department

Temperature diagnostics using lithium-like satellites

Description: A 60-kJ theta-pinch was operated at a filling pressure of 16 mtorr using a gas mixture of 2% neon and 98% helium. The resonance and intercombination lines from Ne IX and the Li-like satellites were observed with a Bragg crystal monochromator. The electron temperature of the plasma was deduced from the intensity ratios of the Ne IX resonance line and the dielectronic satellites using recent theoretical calculations. The temperature values ranged from 210 eV to 340 eV during the time of occurrence of these satellites. The temperature measured at 1.0 ..mu..s by laser scattering for a similar plasma condition was in close agreement with that obtained by the resonance line/satellite ratio. This lends confidence to use of the satellite technique for temperature measurements in other plasmas.
Date: October 1, 1980
Creator: Datla, R.U.; Jones, L.A. & Thomson, D.B.
Partner: UNT Libraries Government Documents Department

Tracer element injection into PDX tokamak for spectral line indentification and localized Doppler temperature measurement

Description: Magnetic dipole lines in ScXIII - XVII and resonance lines of ScXVIII - XIX were observed and identified. Advantages of ion thermometry by means of tracer element injection are described.
Date: October 1, 1980
Creator: Suckewer, S.; Cecchi, J.; Cohen, S.; Fonck, R. & Hinnov, E.
Partner: UNT Libraries Government Documents Department

Diagnostics of inertial confinement fusion experiments

Description: The requirements of plasma temperature and particle energies are effectively the same for inertial confinement fusion, ICF, and magnetic containment fusion, MCF. The n/tau product must also be similar; however, in ICF we increase the density to achieve efficient fuel burn up. Reactor gain pellets are expected to require densities of up to 10/sup 4/ x liquid density of DT. This corresponds to n approximately 10/sup 26/ cm-/sup 3/. The dimensions of the compressed core are of the order of microns. Thus, the diagnostics problems in ICF is to measure plasmas at approximately 10/sup 8/ K, n approximately 10/sup 26/ cm-/sup 3/, on scale lengths of microns with time scales of picoseconds. In this paper we discuss the extensive diagnostics which we have developed to measure the performance of our laser irradiated targets.
Date: August 1, 1977
Creator: Ahlstrom, H.G.
Partner: UNT Libraries Government Documents Department

Comparison of Fresnel zone plates and uniformly redundant arrays

Description: Several imaging systems in laser fusion, e-beam fusion, and astronomy employ a Fresnel zone plate (FZP) as a coded aperture. The recent development of uniformly redundant arrays (URAs) promises several improvements in these systems. The first advantage of the URA is the fact that its modulation transfer function (MTF) is the same as the MTF of a single pinhole, whereas the MTF of an FZP is an erratic function including some small values. This means that if inverse filtering is used, the URA will be less susceptible to noise. If a correlation analysis is used, the FZP will produce artifacts whereas the URA has no artifacts (assuming planar sources). Both the FZP and URA originated from functions which had flat MTFs. However, practical considerations in the implementation of the FZP detracted from its good characteristics whereas the URA was only mildly affected. The second advantage of the URA is that it better utilizes the available detector area. With the FZP, the aperture should be smaller than the detector in order to maintain the full angular resolution corresponding to the thinnest zone. The cyclic nature of the URA allows one to mosaic it in such a way that the entire detector area collects photons from all of the sources within the field of view while maintaining the full angular resolution. If the FZP is as large (or larger) than the detector, all parts of the source will not be resolved with the same resolution. The FZP does have some advantages, in particular its radial symmetry eases the alignment problem; it has a convenient optical decoding method; and higher diffraction order reconstruction might provide better spatial resolution.
Date: January 1, 1978
Creator: Fenimore, E.E.; Cannon, T.M. & Miller, E.L.
Partner: UNT Libraries Government Documents Department

Flat-response x-ray-diode-detector development

Description: In this report we discuss the design of an improved sub-nanosecond flat response x-ray diode detector needed for ICF diagnostics. This device consists of a high Z cathode and a complex filter tailored to flatten the response so that the total x-ray energy below 1.5 keV can be measured using a single detector. Three major problems have become evident as a result of our work with the original LLNL design including deviation from flatness due to a peak in the response below 200 eV, saturation at relatively low x-ray fluences, and long term gold cathode instability. We are investigating grazing incidence reflection to reduce the response below 200 eV, new high Z cathode materials for long term stability, and a new complex filter for improved flatness. Better saturation performance will require a modified XRD detector under development with reduced anode to cathode spacing and increased anode bias voltage.
Date: October 1, 1982
Creator: Tirsell, G.
Partner: UNT Libraries Government Documents Department

Novel target configurations for selective ionization state studies in molybdenum

Description: Details of experiments aimed at achieving low ionization state selectivity in molybdenum are presented. Targets are excited with a 10 J CO{sub 2} laser and the resultant VUV spectrum (300--700 {Angstrom}) has been studied. Combinations of focal spot size, target depth, and target geometries are compared. Simple attenuation of energy is shown not to vary ionization stage composition significantly. Experiments conducted with grazing incidence targets result only in a hot plasma. Modular targets with cooling cylinders of various radii demonstrated good selectivity of the ionization states, but with low absolute signals. Finally, results from combinations of focal spot adjustment and radiative cooling illustrate increased control over desired plasma temperature and density for spectroscopic studies of molybdenum. 7 refs., 14 figs.
Date: March 1, 1990
Creator: Ilcisin, K.J.; Feldman, U.; Schwob, J.L.; Wouters, A. (Princeton Univ., NJ (USA). Plasma Physics Lab.) & Suckewer, S. (Princeton Univ., NJ (USA). Plasma Physics Lab. Princeton Univ., NJ (USA). Dept. of Mechanical and Aerospace Engineering)
Partner: UNT Libraries Government Documents Department