Measured response of bubble neutron detectors and prospects for alpha knock-on diagnostics

Fisher, R. K.; Parks, P.B.; Liptac, J.; Belian, Anthony P.; Morse, Edward; Ingram, David C.; Brient, C. E.; Medley, S. S.; Roquemore, A. L.; Loughlin, M. L.

doi:10.1063/1.1319870

Cited by 10 publications

(5 citation statements)

References 6 publications

(6 reference statements)

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“…Due to the larger solid angle, the image from a penumbral aperture is formed from many more neutrons than for a pinhole; for a given yield, the S/N ratio is intrinsically higher. 12 The coded image must be deconvolved to produce an image of the neutron source. This process requires precise knowledge of the aperture point-spread function and the flatfield response of the imaging detector.…”

Section: B Penumbral Imagingmentioning

confidence: 99%

Aperture tolerances for neutron-imaging systems in inertial confinement fusion

Ghilea

Sangster

Meyerhofer

et al. 2008

Review of Scientific Instruments

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Neutron-imaging systems are being considered as an ignition diagnostic for the National Ignition Facility (NIF) [Hogan et al., Nucl. Fusion 41, 567 (2001)]. Given the importance of these systems, a neutron-imaging design tool is being used to quantify the effects of aperture fabrication and alignment tolerances on reconstructed neutron images for inertial confinement fusion. The simulations indicate that alignment tolerances of more than 1 mrad would introduce measurable features in a reconstructed image for both pinholes and penumbral aperture systems. These simulations further show that penumbral apertures are several times less sensitive to fabrication errors than pinhole apertures.

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Section: B Penumbral Imagingmentioning

confidence: 99%

Aperture tolerances for neutron-imaging systems in inertial confinement fusion

Ghilea

Sangster

Meyerhofer

et al. 2008

Review of Scientific Instruments

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“…One proposal, which has been successfully tested on JET [43], is to measure the high energy neutron tail produced by alpha knock-on energetic ions. This tail can potentially be measured using a neutron spectrometer, such as a magnetic proton recoil spectrometer, [43], a bubble detector [44,45] or a nuclear emulsion track detector [46]. The discrimination of the alpha knock-on neutrons from beam particle knock-on neutrons is a potential problem that needs to be addressed.…”

Section: Fusion Product Measurementsmentioning

confidence: 99%

Chapter 7: Diagnostics

et al. 2007

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In order to support the operation of ITER and the planned experimental programme an extensive set of plasma and first wall measurements will be required. The number and type of required measurements will be similar to those made on the present-day large tokamaks while the specification of the measurements-time and spatial resolutions, etc-will in some cases be more stringent. Many of the measurements will be used in the real time control of the plasma driving a requirement for very high reliability in the systems (diagnostics) that provide the measurements.The implementation of diagnostic systems on ITER is a substantial challenge. Because of the harsh environment (high levels of neutron and gamma fluxes, neutron heating, particle bombardment) diagnostic system selection and design has to cope with a range of phenomena not previously encountered in diagnostic design. Extensive design and R&D is needed to prepare the systems. In some cases the environmental difficulties are so severe that new diagnostic techniques are required.The starting point in the development of diagnostics for ITER is to define the measurement requirements and develop their justification. It is necessary to include all the plasma parameters needed to support the basic and advanced operation (including active control) of the device, machine protection and also those needed to support the physics programme. Once the requirements are defined, the appropriate (combination of) diagnostic techniques can be selected and their implementation onto the tokamak can be developed. The selected list of diagnostics is an important guideline for identifying dedicated research and development needs in the area of ITER diagnostics.This paper gives a comprehensive overview of recent progress in the field of ITER diagnostics with emphasis on the implementation issues. After a discussion of the measurement requirements for plasma parameters in ITER and their justifications, recent progress in the field of diagnostics to measure a selected set of plasma parameters is presented. The integration of the various diagnostic systems onto the ITER tokamak is described. Generic research and development in the field of irradiation effects on materials and environmental effects on first mirrors are briefly presented. The paper ends with an assessment of the measurement capability for ITER and a forward of what will be gained from operation of the various diagnostic systems on ITER in preparation for the machines that will follow ITER. Performance assessment relative to requirements Design meets requirements S339 A.J.H. Donné et alPhysics Basis [7] and remains essentially the same. However, for ITER, the specific limits have changed. 2.1.2.Measurements needed for plasma control and evaluation. The measurements needed for plasma control and evaluation are naturally directly linked to the experimental programme, and particularly to the operating phase (i.e. H, D or D/T) and the operating scenario (H-mode, hybrid, etc). Since there is expected to be a phased introduction of po...

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“…It is difficult to see how such a spectrometer could provide sufficient counts for both adequate temporal or spatial resolution. Hence a development of a set of pulsed bubble chamber detectors, with very sharp low-energy cut-offs, the lowest at about 15 MeV, so that only the "knock-on" tail's spectrum is measured, has been proposed 15 . The detectors could be installed in collimator tubes of a neutron camera for a BP device.…”

Section: Measurements Of Confinement and Slowing Down: Effect Of Plasmentioning

confidence: 99%