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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1044-1046 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The total abundance of secondary ion current detected from a heavy ion beam probe (proportional to nσeff ) is a function of the electron temperature through the collision cross section. n and Te can be separated by probing the same volume with two different ion species or monitoring two different charge states produced from the same ion. Measurements at Rensselaer (RENTOR) have demonstrated the technique by using a single detector system to look at Cs++ and Cs+++ on successive plasma shots. Data from EBT-S has shown a sensitivity to electron energies up to 1 MeV, but accurate determination of bulk temperatures is limited to a few hundred volts. Two new analyzers have been installed on RENTOR to demonstrate the capability of providing Te profiles during a single shot. Calibration of these measurements requires a detailed accounting of all input beam ions, reaction products, and sample volumes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1828-1830 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A heavy ion beam probe has been operated with two separate electrostatic energy analyzers to allow simultaneous detection of 2+ and 3+ secondary ions coming from a singly charged probing beam. This configuration provides rapid, spatially resolved measurements of the electron temperature for Te ≤200 eV, and measurements of the correlation between density and space potential fluctuations from two separate locations in the plasma. The possibility of electron temperature fluctuations can also be investigated. Since the spatial location of the measurements can be varied, the correlation length in both the kr and kθ directions can be determined.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Many of the diagnostics that work on present magnetic fusion experiments will fail badly in the high radiation field of the burning fusion devices which are under conceptual design now. Two quantities of particular interest are the poloidal magnetic field profile versus minor radius, and radial measurements of β near the plasma center. Knowledge of the poloidal magnetic field is sufficient to infer the q profile and/or the current profile which is vital to understanding the MHD stability of the plasma and controlling the current profile. Knowledge of the ratio β of the plasma pressure to the magnetic field pressure radially resolved in the vicinity of the plasma center is also extremely useful for control and diagnosis of the plasma. A proposed new diagnostic uses crossed-sightline correlation of the thermal fluctuations in the electron cyclotron radiation emitted by the plasma to infer the local magnetic field very accurately. The field is measured at the crossing point of two sightlines into the plasma. The sightlines cross at small angles, typically 8° at the plasma center to about 18° at the plasma edge. By scanning the mirrors defining the two sightlines the absolute magnetic field across the plasma minor radius can be measured to an accuracy of better than 1 part in 103, with time resolution of the order of 10 ms per data point. This allows calculation of the q profile over most of the minor radius to an accuracy of better than 10% (given density and temperature measurements), and extremely accurate measurements of the plasma beta from r/a=0 to r/a=0.2.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3528-3531 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A neutral beam diagnostic system has been designed to do simultaneous space potential and density measurements in the tokamak plasma edge to complement existing probe diagnostics. Rapid radial profiles are possible by computer control of the energy and the injection angle of the neutral beam. A particular application under consideration is the Tokamak de Varennes, which is presently being upgraded to operate either as a limiter or as a divertor machine. In this application, an ion gun is used to produce a Tl+1 beam that can be steered radially and toroidally to scan the plasma edge. The ion beam is neutralized downstream in a charge-exchange cell and the resulting Tl neutral beam is injected through a side port into the plasma. Singly charged Tl ions produced in the plasma exit through a top port of the tokamak and are collected by an electrostatic energy analyzer. Numerical simulations of the trajectories show that beam energies between 40 and 55 keV are sufficient to probe the plasma edge radially from 23 to 29 cm with a few millimeters resolution. The use of a neutral beam allows measurements in a tokamak edge plasma with BT∼1.0 T with a reduction in beam energy by more than a factor of 3 compared to the use of ion beams. Details of the beam probe hardware and the Tokamak de Varennes application are presented.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3308-3308 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Progress in the magnetic fusion programs has driven and been driven by the development of sophisticated diagnostic systems. The application of state of the art technologies has resulted in major strides in detailed measurements of plasma characteristics. We present the details of design studies carried out to develop specialized instrumentation. For application to optical spectroscopy, a compact multichannel spectroscopic monitor is described. This instrument is designed for simultaneous observation of plasma emissions from a variety of spatial locations. The heart of the system is an optical filter mosaic and MCP/CCD array. Applications include impurity emission monitoring, particle inventory, and working gas fraction measurements in minority heating experiments. The second instrument includes a detector design for application to high time resolution measurements of electron cyclotron emissions. The system is based on arrays of slot-antennae/detectors manufactured on single semiconductor wafers. This millimeter-wave monolithic integrated circuit (MMIC) device can be tailored to detect radiation in the 50–300 GHz range typical of tokamak plasmas. Advantages include uniformity of detector response, spectral resolution without gratings, and high spatial resolution. Details of both designs will be discussed with emphasis on ranges of application in present and next generation machines.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2987-2987 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A neutral beam diagnostic system has been designed to do simultaneous space potential and density measurements in the tokamak plasma edge to complement existing probe diagnostics. Rapid radial profiles are possible by computer control of the energy and the injection angle of the neutral beam. A particular application under consideration is the Tokamak de Varennes, which is presently being upgraded to operate either as a limiter or as a divertor machine. In this application, an ion gun is used to produce a Tl+1 beam that can be steered radially and toroidally to scan the plasma edge. The ion beam is neutralized downstream in a charge-exchange cell and the resulting Tl neutral beam is injected through a side port into the plasma. Singly charged Tl ions produced in the plasma exit through a top port of the tokamak and are collected by an electrostatic energy analyzer. Numerical simulations of the trajectories show that beam energies between 40 and 55 keV are sufficient to probe the plasma edge radially from 23 to 29 cm with a few millimeters resolution. The use of a neutral beam allows measurements in a tokamak edge plasma with BT∼1.0 T with a reduction in beam energy by more than a factor of 3 compared to the use of ion beams. Details of the beam probe hardware and the Tokamak de Varennes application are presented.
    Type of Medium: Electronic Resource
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