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  • 1
    Electronic Resource
    Electronic Resource
    Stark-effect measurement of high free-electron laser electric fields in MTX by laser-aided particle-probe spectroscopy : Eighth topical conference on high−temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2964-2966 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We are constructing a diagnostic system to measure the electric field ((approximately-greater-than)100 kV/cm) of a free-electron laser (FEL) beam when injected into the plasma of the Microwave Tokamak Experiment (MTX). The apparatus allows a crossed-beam measurement, with 2 cm spatial resolution in the plasma, involving the FEL beam (with 140 GHz, ≈1 GW ECH pulses), a neutral helium beam, and a dye laser beam. After the laser beam pumps metastable helium atoms to higher excited states, their decay light is detected by an efficient optical system. Because of the Stark effect arising from the FEL electric field (E), a forbidden transition can be strongly induced. The intensity of emitted light resulting from the forbidden transition is proportional to E2. Because photon counting rates are estimated to be low, extra effort is made to minimize background and noise levels. It is possible that the lower E of an MTX gyrotron-produced ECH beam with its longer duration pulses can also be measured using this method. Other applications of the apparatus described here may include measurements of ion temperature (using charge-exchange recombination), edge-density fluctuations, and core impurity concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141740
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  • 2
    Electronic Resource
    Electronic Resource
    Design of the divertor Thomson scattering system on DIII-D : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 493-495 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Local measurements of ne and Te in the divertor region are necessary for a more complete understanding of divertor physics. We have designed an extension to the existing multipulse Thomson scattering system [Carlstrom et al., Rev. Sci. Instrum. 63, 4901 (1992)] to measure ne in the range 5×1018–5×1020 m−3 and Te in the range 5–500 eV with 1 cm resolution from 1 to 21 cm above the floor of the DIII-D vessel (eight spatial channels) in the region of the X point for lower single-null diverted plasmas. One of the existing, 20 Hz, Nd:YAG lasers will be redirected to a separate vertical port and viewed radially with a specially designed f/6.8 lens. Fiber optics carry the light to polychromators whose interference filters have been optimized for low Te measurements. Other aspects of the system, including the beam path to the vessel, polychromator design, real-time data acquisition, laser control, calibration facility, and DIII-D timing and data acquisition interface, will be shared with the existing multipulse Thomson system. An in situ laser alignment monitor will provide alignment information for each laser pulse. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146534
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  • 3
    Electronic Resource
    Electronic Resource
    E(parallel)B end-loss-ion analyzer for Tandem-Mirror Experiment-Upgrade (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1117-1119 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We are constructing and testing a diagnostic instrument to investigate, in detail, ions emanating along magnetic field lines from the plasma region of the TMX-U tandem-mirror experiment. This analyzer (of Tokamak Fusion Test Reactor design) contains parallel electric and magnetic fields, which yield ion mass and energy spatial separation, respectively. A two-dimensional array of 128 copper collector plates detects the particles. The entering ion flux is first well collimated and then focused onto the detector plane during the 180° bending in the magnetic field. This instrument is designed to measure higher particle energies than the present gridded end-loss analyzers as well as determine the energy spectra more accurately. Tandem-mirror plasma parameters to be investigated with this analyzer include end-plug potential, average central-cell-ion energy, and plasma potential in the thermal barrier and nearby regions. We plan a time resolution of up to 2 kHz for each detector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138242
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  • 4
    Electronic Resource
    Electronic Resource
    Plasma measurements with the TMX-U E(parallel)B end-loss-ion spectrometers (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1786-1788 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two E(parallel)B end-loss-ion spectrometers (ELIS) are now making plasma measurements on tandem mirror experiment-upgrade (TMX-U). One instrument is mounted on each end of this open-ended tandem-mirror machine. These spectrometers observe plasma losses along magnetic-field lines. They operate reliably and with a minimum of attention during an experimental run. Their data, which are quickly acquired and analyzed, help guide the experimental sequence. The parallel electric and magnetic fields separate the end-loss ions according to mass (D+ and H+) and energy. Each spectrometer detects ions with an array of 128 flat collector plates that are made from copper-coated G10 epoxy fiberglass, normally used for printed-circuit boards. The ELIS diagnostic system produces a wealth of experimental information, including data on peak plasma potential, central-cell ion temperature, potentials in the thermal-barrier region, axial confinement and ion-end-loss plugging, energetic-electron losses, and hydrogen/deuterium concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139182
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  • 5
    Electronic Resource
    Electronic Resource
    Determining plasma-fueling sources with an end-loss ion spectrometer (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1783-1785 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To help identify the major sources of fueling gas in Tandem Mirror Experiment-Upgrade (TMX-U), we mounted a mass-sensitive, E||||B, end-loss ion spectrometer (ELIS) near the machine's centerline. We set the electric field in the ELIS to simultaneously measure the axial loss currents of both hydrogen and deuterium. We then initiated plasma discharges, where we injected either hydrogen or deuterium gas into the central cell. We also selected and deselected the central-cell neutral beams that were fueled with hydrogen gas. The end-cell neutral beams were always selected and fueled with deuterium. By taking the ratio of the hydrogen end-loss current to the deuterium end-loss current (with a known deuterium-gas feed rate), we were able to infer the effective fueling rates that were due to wall reflux, central-cell beams, and end-cell beams. The results were the following: wall reflux, 6 Torr l/s; central-cell beams, 15 Torr l/s; and end-cell beams 1 Torr l/s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139181
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  • 6
    Electronic Resource
    Electronic Resource
    Operation of an E (parallel) B end-loss ion spectrometer on the Tara tandem mirror (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1664-1666 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An E (parallel) B end-loss ion spectrometer from the Livermore TMX-U tandem mirror experiment was installed on Tara for high-resolution ion spectroscopy. This diagnostic contains parallel electric and magnetic fields, separating the masses and energies of the ions over 128 collector plates. The ion energy distribution nominally yields confining potentials and parallel ion temperatures. Additional experiments have diagnosed the resonance position of the central cell ion cyclotron heating, rf enhanced losses of high-energy sloshing ions in the axicell ("plug''), and observation of MHD instabilities at higher time resolution (20 kHz).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140126
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  • 7
    Electronic Resource
    Electronic Resource
    Thomson scattering diagnostic for the microwave tokamak experiment : Eighth topical conference on high—temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2861-2863 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Thomson scattering diagnostic system (TSS) on the microwave tokamak experiment (MTX) at LLNL routinely monitors electron temperature (Te) and density. Typical measured values at the plasma center under clean conditions are 900±70 eV and 1–2×1014 (±30%) cm−3. The TSS apparatus is compact, with all elements mounted on one sturdy, two-level optics table. Because of this, we maintain with minimum effort the alignment of both the ruby-laser input optics and the scattered-light collecting optics. Undesired background signals, e.g., plasma light as well as ruby-laser light scattered off obstacles and walls, are generally small compared with the Thomson-scattered signals we normally detect. In the MTX Te region, the TSS data are definitely fitted better when relativistic effects are included in the equations. Besides determining the temperature of the Maxwellian electron distribution, the system is designed to detect electron heating from GW-level free-electron laser (FEL) pulses by measuring large wavelength shifts of the scattered laser photons. TSS data suggest that we may indeed be able to detect these electrons, which can have energies up to 10 keV, according to computer simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141807
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  • 8
    Electronic Resource
    Electronic Resource
    TMX upgrade magnet system: Design characteristics and physics considerations (1982)
    Springer
    Journal of fusion energy 2 (1982), S. 383-402 
    Details
    ISSN: 1572-9591
    Keywords: tandem mirror ; magnetic mirror ; controlled thermonuclear fusion ; thermal barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Summarized in this article are the design characteristics of the magnet-system configuration constructed for use in the modified Tandem Mirror Experiment (TMX Upgrade), and a description of the resulting vacuum magnetic field. Many engineering and physics considerations and limitations governed the design. Several of the physics issues are discussed here, including single-particle drift surfaces and adiabaticity, central-cell resonant radial transport, magnetohydrodynamic stability analysis, and finite-beta equilibrium. The described design procedures can be applied to other tandem-mirror experiments or reactor studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053133
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