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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1999-1999 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Plasmas have been formed in the tokamak fusion test reactor (TFTR) which separate completely from the limiter and are called detached plasmas. The physical evidence for the separation from the limiter is that all the ohmic input power is radiated away at the plasma boundary which can be 10→30 cm inside the limiter. The 10-chord multichannel MIRI interferometer system has been used to diagnose this region and follows the formation of the detached state through a MARFE. MIRI indicates that a plasma ∼0.5→1×1013 cm−3 occurs in the region between the luminous boundary and the limiter. This work was supported by U.S. DOE Contract No. DE-AC02-76-CHO-3073.
    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 59 (1988), S. 1869-1871 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Co- and counter-viewing bolometers aimed along a common tangency chord are being used to study power losses due to charge exchange (CX) of fast ions in neutral beam injection (NBI) heated TFTR plasmas. For unidirectional injection, tangential bolometers oriented to view CX loss of circulating fast ions detect losses from the thermal target plasma (impurity radiation and CX) plus power due to the fast ion CX loss, whereas bolometers oppositely directed measure only the target plasma contribution. The difference between the two signals is a measure of the fast ion CX loss. Additional information is obtained by comparing the tangential bolometer signals with those of perpendicularly viewing bolometer monitors and arrays. The measurements are compared to results of the TRANSP code analysis.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1872-1874 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Designing bolometers for Compact Ignition Tokamak presents difficult, perhaps insurmountable, challenges. Detector environment will be quite harsh, viewing access will be severely limited, and, most importantly, the heating of detectors by neutron and gamma radiation will be larger than that by the radiation losses to be measured. Furthermore, the radiation losses themselves will no longer be dominated by impurity radiation as in earlier machines, but will be a combination of impurity radiation, bremsstrahlung, and synchrotron radiation. Possible approaches to a design have been developed, based on optimizing the response to VUV- and x-radiation, possible local shielding, subtraction of the n and γ heating, constant in situ calibration, and deployment of the detectors in a tangentially viewing array. The array makes it possible to cover the plasma cross section, as well as to see into the divertors. Estimates indicate that it should be possible to make successful measurements of the two-dimensional radiation loss profile.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 4583-4593 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The TRANSP code [R. V. Budny et al., Nucl. Fusion 35, 1497 (1995)] is used to construct comprehensive, self-consistent models for plasmas within the separatrix surface in the International Thermonuclear Experimental Reactor (ITER) [Technical Basis for the ITER Interim Design Report, Cost Review and Safety Analysis (International Atomic Energy Agency, Vienna, 1996)]. Steady state profiles of two plasmas from the ITER "Interim Design'' database are used. Effects of 1 MeV neutral beam injection, sawteeth mixing, toroidal field ripple, and helium ash transport are included. Results are given for the fusion rate profiles, and parameters describing effects such as the alpha particle heating of electrons and thermal ions, and the thermalization rates. The modeling indicates that the deposition of the neutral beam ions will peak in the plasma center, and the average beam ion energy will be half the injected energy. Sawtooth mixing will broaden the fast alpha profile. The toroidal ripple loss rate of alpha energy will be 3% before sawtooth crashes and will increase by a factor of 3 immediately following sawtooth crashes. Various assumptions for the thermal He transport and the He recycling coefficient at the separatrix Rrec are used. If the ratio of helium and energy confinement times, τ*He/τE is less than 15, the steady state fusion power is predicted to be 1.5 GW or greater. The values of the transport coefficients required for this fusion power depend on Rrec. If this is larger than about 0.5, and if the inward pinch is small the required He diffusivity must be much larger than that measured in tokamaks. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3857-3870 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analytic model is developed to estimate the classical pitch angle scattering loss of energetic fusion product ions into prompt loss orbits in a tokamak geometry. The result is applied to alpha particles produced by deutrium–tritium fusion reactions in a plasma condition relevant to Tokamak Fusion Test Reactor (TFTR) [Proceedings of the 14th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Würzburg, 1992 (International Atomic Energy Agency Vienna, 1992)]. A poloidal angular distribution of collisional fast ion loss at the first wall is obtained and the numerical result from the transp ["A standard D–T supershot simulation'' (to be published in Nucl. Fusion, 1994)] code is discussed. The present model includes the effect that the prompt loss boundary moves away from the slowing-down path due to reduction in banana thickness, which enables one to understand, for the first time, the dependence of the collisional loss rate on Zeff. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The confinement and heating of supershot plasmas are significantly enhanced with tritium beam injection relative to deuterium injection in the Tokamak Fusion Test Reactor [Plasma Phys. Controlled Fusion 26, 11 (1984)]. The global energy confinement and local thermal transport are analyzed for deuterium and tritium fueled plasmas to quantify their dependence on the average mass of the hydrogenic ions. Radial profiles of the deuterium and tritium densities are determined from the D–T fusion neutron emission profile. The inferred scalings with average isotopic mass are quite strong, with τE∝〈A〉0.85±0.20, τEthermal∝〈A〉0.89±0.20, χitot∝〈A〉−2.6±0.5, and De∝〈A〉−1.4±0.2 at fixed Pinj. For fixed local plasma parameters χitot∝〈A〉−1.8±0.4 is obtained. The quoted 2σ uncertainties include contributions from both diagnostic errors and shot irreproducibility, and are conservatively constructed to attribute the entire scatter in the regressed parameters to uncertainties in the exponent on plasma mass. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 3237-3237 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the Tokamak Fusion Test Reactor (TFTR) [International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Wurzburg, Paper No. A-2-2 (International Atomic Energy Agency, Vienna, 1993)] there have been at least three types of anomalous loss of alpha-like deuterium–deuterium (D–D) fusion products: (1) a magnetohydrodynamic (MHD)-induced loss of D–D fusion products correlated with Mirnov and fishbone-type oscillations and sawtooth crashes, (2) a slow "delayed'' loss of partially thermalized D–D fusion products occurring without large MHD activity, and (3) ion cyclotron resonance heating (ICRH)-induced loss of D–D fusion products ions observed during direct electron heating experiments, and possibly also during 3He minority heating. In this paper each of these will be reviewed, concentrating on those due to MHD activity, which are the largest of these anomalous losses. The experimental results are compared with numerical models of various fusion product transport mechanisms.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of isotope on confinement in high-recycling, L-mode plasmas is studied on the Tokamak Fusion Test Reactor (TFTR) [see D. M. Meade, J. Fusion Energy 7, 107 (1988)] by comparing hydrogen and deuterium plasmas with the same magnetic field and similar electron densities and heating power, with both Ohmic and deuterium-neutral-beam heating. Following a long operational period in deuterium, nominally hydrogen plasmas were created through hydrogen glow discharge and hydrogen gas puffing in Ohmic plasmas, which saturated the exposed limiter surface with hydrogen and raised the H/(H+D) ratio from 10±3% to 65±5%. Ohmic deuterium discharges obtained higher stored energy and lower loop voltage than hydrogen discharges with similar limiter conditions. Neutral-beam power scans were conducted in L-mode plasmas at minor radii of 50 and 80 cm, with plasma currents of 0.7 and 1.4 MA. To minimize transport differences from the beam deposition profile and beam heating, deuterium neutral beams were used to heat the plasmas of both isotopes. Total stored energy increased approximately 20% from nominally hydrogen plasmas to deuterium plasmas during auxiliary heating. Of this increase about half can be attributed to purely classical differences in the energy content of unthermalized beam ions. Kinetic measurements indicate a consistent but small increase in central electron temperature and total stored electron energy in deuterium relative to hydrogen plasmas, but no change in total ion stored energy. No significant differences in particle transport, momentum transport, and sawtooth behavior are observed. Overall, only a small improvement (∼10%) in global energy confinement time of the thermal plasma is seen between operation in hydrogen and deuterium. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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