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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 569-572 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutron diagnostics will play a prominent role in the control and evaluation of thermonuclear plasmas in ignition device to test engineering concepts (ITER). As in present D-T experiments, measurements of neutron yield and of fusion power and power density are essential. In addition, the spectral width of the 14.1-MeV t(d,n)α neutron emission should be a reliable indicator of ion temperature in an ignited plasma. More detailed measurements of the neutron spectrum may allow determination of the densities of tritium, deuterium, and confined alpha particles. Although the central fusion power density in ITER will be comparable to the maximum values obtainable in TFTR and JET, neutron flux on the first wall will be ten times higher, and the neutron yield per discharge will be about five orders of magnitude greater than previously experienced. The thermal and radiation shielding necessary to protect the ITER superconducting coils from the intense flux at the first wall will restrict diagnostic access for neutron cameras and spectrometers, complicate the design of material activation systems, and limit the applicability of conventional calibration techniques for neutron source strength monitors. These considerations, together with unprecedented reliability requirements and the need for full remote handling of many components, pose demanding challenges for the design of the ITER neutron diagnostic systems. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The JET neutron profile monitor was used to study the transport of tritium into a magnetically confined deuterium plasma. Trace amounts of tritium were introduced through a gas valve beyond the plasma edge into a variety of plasma confinement regimes. The d(t,n)α fusion cross section is two orders of magnitude greater than the d(d,n)3He cross section and so a puff of tritium which has a negligible effect on the plasma nevertheless produces a large d–t neutron signal. The profile monitor consists of two cameras each made up of a fan-shaped array of collimated lines of sight. It was used to measure the d–d and d–t neutron profiles simultaneously. This article describes the detection system, its operation and assesses the difficulties due to scattered neutrons. The profiles can be used to determine tritium density and transport coefficients. © 1999 American Institute of Physics.
    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: Neutron cameras with horizontal and vertical views have been designed for ITER, based on systems used on JET and TFTR. The cameras consist of fan-shaped arrays of collimated flight tubes, with suitably chosen detectors situated outside the biological shield. The sight lines view the ITER plasma through slots in the shield blanket and penetrate the vacuum vessel, cryostat, and biological shield through stainless steel windows. This article analyzes the expected performance of several neutron camera arrangements for ITER. In addition to the reference designs, we examine proposed compact cameras, in which neutron fluxes are inferred from 16N decay gammas in dedicated flowing water loops, and conventional cameras with fewer sight lines and more limited fields of view than in the reference designs. It is shown that the spatial sampling provided by the reference designs is sufficient to satisfy target measurement requirements and that some reduction in field of view may be permissible. The accuracy of measurements with 16N-based compact cameras is not yet established, and they fail to satisfy requirements for parameter range and time resolution by large margins. © 1999 American Institute of Physics.
    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 68 (1997), S. 514-519 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Based upon JET experience, the measurement of multichannel collimated neutron fluxes and of the neutron spectrum gives time-dependent information on spatial profiles of neutron emission and alpha–particle birth, the total neutron emission (fuel burn-up rate), plasma position, effects of plasma instabilities, triton burn-up, ion temperature, and fuel densities. The design for a horizontally viewing neutron camera for ITER is based upon the prototype and upgrade versions of the JET neutron emission profile monitor and the JET spectrometers. It is proposed that vertically stacked modules are installed in the ITER biological shield in a fan shaped viewing geometry, aimed at a focal point located at the slit opening of a preshield designed to reduce the streaming neutron flux. Each module contains a pair of sight lines with adjustable collimation, allowing for multiple detector neutron flux monitoring and neutron spectroscopy over a wide operating range. The modular system allows flexibility in detector choice and viewing geometry. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 29 (1988), S. 5217-5220 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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