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  • 1
    Electronic Resource
    Electronic Resource
    Edge temperature and density measurements by helium line intensity ratios in the reversed field experiment RFX with high time resolution : Papers from the thirteenth topical conference on high temperature plasma diagnostics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 967-970 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In the reversed field experiment the electron temperature and density at the edge are measured from the intensity ratio of selected lines emitted by an atomic helium beam injected into the plasma. Helium is injected through a single microtube 30 mm long and with 150 μm of internal diameter. Four beam splitters allow three interference filters, coupled to linear array cameras or alternatively to photomultipliers, and a charge coupled device camera to observe the same beam volume. The application of photomultipliers as detectors has recently increased the time resolution of the diagnostic. This allows following the time evolution of edge density and temperature during nonstationary processes. Moreover, the enhanced time resolution increases the capability of the diagnostic to measure the edge electron temperature and density fluctuations, which are relevant to the edge electrostatic transport studies. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1319600
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  • 2
    Electronic Resource
    Electronic Resource
    Requirements for an active spectroscopy diagnostic with neutral beams on the RFX reversed field pinch : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 861-864 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The conceptual feasibility of an active spectroscopic diagnostic on reversed field experiment (RFX) to measure the radial profiles of ion temperature, toroidal and poloidal drift velocities, and main impurity densities is examined. In particular a charge exchange recombination spectroscopy experiment is simulated for carbon and helium impurities. The motional Stark effect on the beam atoms injected into RFX is estimated as a means to measure the magnetic field pitch and intensity. A modulated beam injector (500 Hz) with 2 A of equivalent current and an energy of 50 keV/amu appears to be adequate to perform the measurements over a reasonable range of operational regimes. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149518
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  • 3
    Electronic Resource
    Electronic Resource
    A pellet ablation diagnostic system for the RFX reversed field pinch : 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. 616-618 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In view of the installation of a multiple pellet injector on the RFX experiment, an integrated diagnostic system has been designed to monitor the pellet behavior in the plasma. The evidence in the reversed field pinches (RFPs) of large poloidal and toroidal pellet deflections along magnetic field lines due to asymmetric ablation, calls for a 3D system with good space and time resolution. Two arrays of Hα detectors will view the trajectories of the pellets from below and from behind and a digital charged coupled device (CCD) camera will view the injection poloidal section from a tangential viewpoint. The two systems will allow the complete determination of the time-resolved trajectory of each pellet. The space integrated Hα emission rate will be measured by a large angle detector and by a space integration of the CCD camera measurement. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146304
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  • 4
    Electronic Resource
    Electronic Resource
    Absolute calibration of a vacuum Czerny–Turner spectrometer in the range 1200–7000 A(ring) : 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. 613-615 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The vacuum Czerny–Turner high-resolution spectrometer observing the plasma of the reversed-field-pinch device RFX has been absolutely calibrated in the spectral range 1215–7000 A(ring), in order to measure the emission spectrum in absolute units, with particular reference to the heliumlike carbon and oxygen ion lines. The source used to calibrate the spectrometer in the vacuum and near-ultraviolet region is a deuterium lamp; its spectral radiance was determined by comparison with the synchrotron radiation of the electron storage ring BESSY, in Berlin. A typical error of 35% has been estimated. In the visible a standard tungsten lamp has been used. The calibration has been transferred to an ultragrazing incidence XUV spectrometer by means of the branching-ratio technique, using the intensity ratio between the intercombination 1s2 1S–1s2p 3P0 and the 1s2s 3S–1s2p 3P0 transitions of carbon, nitrogen, and oxygen heliumlike ions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146303
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  • 5
    Electronic Resource
    Electronic Resource
    The ultra-soft x-ray multilayer mirror-based duochromator for the reverse field experiment reversed field pinch experiment : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1043-1046 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The ultra-soft x-ray duochromator based on two multilayer mirrors installed on the reversed field pinch experiment (RFX) reversed field pinch is described. Built at the Budker Institute of Nuclear Physics of Novosibirsk, it has been designed to monitor the time behavior of the hydrogen and helium-like resonant transitions of carbon and oxygen, the main impurities in the RFX emission spectrum, with the possibility of scanning the wavelengths between 16 and 45 Å. The wavelengths can be independently selected for both the mirrors (made of Ni/C and Cr/C layers, respectively) via a aitch-theta–2aitch-theta mechanism, without breaking the vacuum. The detector is based on a scintillator layer deposited on the head of a photomultiplier. Vacuum ultraviolet and visible radiation is cut by means of thin metal films (Fe, Al, Cr) deposited on a mylar substrate and on the scintillator. The wavelength resolution (λ/Δλ) of 40 to 50 in the region of interest is provided by a Soller collimator and a precollimator stage placed in front of the mirror. The relatively large etendue allows one to perform observation in a wide range of experimental conditions. Sample results of the chordal observations are compared in absolute units with the predictions of a collisional–radiative one-dimensional impurity transport code. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147783
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  • 6
    Electronic Resource
    Electronic Resource
    Impurity influx diagnostics on RFX : 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. 610-612 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The systems installed on the RFX reversed field pinch to study the impurity influxes are described. They comprise of telescope lenses, coupled through optical fibers and interference filters or spectrographs to photomultipliers for time-resolved analysis, and charge coupled device (CCD) cameras. The solutions adopted aim at giving an insight into the impurity production mechanisms in a situation characterized by largely asymmetric plasma–wall interactions. Main gas and various impurity influxes from the same area of the first wall are compared by means of very simple light splitters interposed between telescope lenses and narrow band filters. Four high-resolution CCD cameras also equipped with interference filters cover more than half of the first wall allowing detailed spatial studies of the impurity influx distributions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146302
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  • 7
    Electronic Resource
    Electronic Resource
    A wide wavelength range spectrometer (1150–8000 A(ring)) for the RFX reversed field pinch experiment : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5188-5190 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the vacuum Czerny–Turner spectrometer with a 1.33 m focal length installed on the RFX fusion experiment. The optics are coated with MgF2 and the image intensifier, protected by a vacuum sealed MgF2 window, features a dual photocathode system, CsTe on one half and S20 on the other; thus the instrument covers efficiently the wide spectral range from the MgF2 limit to the near infrared. Sensitivity at short wavelengths is limited by the reflectance of mirrors and the transmittance of the MgF2 window. The detector is completed by a fast optical multichannel analyzer whose 1024 photodiodes can be read out in a time of 250 μs. The instrument can also be operated in a duochromator mode by deflecting the diffracted beam onto a second detector system, where two photomultipliers are applied to two exit slits, one fixed and the other remotely movable in such a way that the intensity ratios of two lines can be monitored for diagnostic purposes. Some examples of obtained spectra illustrating the instrument performance and comprising first results from the RFX plasma are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143425
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  • 8
    Electronic Resource
    Electronic Resource
    Experimental measurements and modelling of the structure of the radial electric field in RFX (2000)
    Springer
    Czechoslovak journal of physics 50 (2000), S. 1387-1396 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The experimental determination of the radial electric field E r and the associated E × B drift velocity at the edge of RFX is presented and possible mechanisms responsible for its generation are discussed. E r measurements by means of an array of Langmuir probes and those deduced from Doppler spectroscopy of impurity lines agree fairly well. In particular the rotation velocity of the plasma edge has been determined from the Doppler shift of a C III emission line. The observation of other ions characterised by different radial positions, such as B IV and C V, has allowed an estimate of the velocity shear. Typical values of plasma rotation at the edge are around 10 km/s while the velocity shear is of the order of (105–106)s−1 in the spontaneous layer, a few cm thick, usually observed in standard discharges. Plasma rotation has been artificially modified by both positive and negative edge biasing and the associated increase or decrease of the fluid velocity is well in agreement with the radial electric field change. The modification of E r during edge biasing and Pulsed Poloidal Current Drive (PPCD) are also reported and interpreted within a momentum balance model. Analytical and self-consistent Monte Carlo models at the plasma edge suggest that impurities have a relevant role in the generation of the radial electric field, due to their relatively large Larmor radius.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022843529120
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