Observation of the Alpha Particle “Knock-On” Neutron Emission from Magnetically Confined DT Fusion Plasmas

Källne, J.; Ballabio, L.; Frenje, J. A.; Conroy, S.; Ericsson, Göran; Tardocchi, M.; Traneus, E.; Gorini, G.

doi:10.1103/physrevlett.85.1246

Cited by 103 publications

(128 citation statements)

References 14 publications

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“…Calculations for ITER show NPA count rates up to 10 4 s −1 for deuterons of E > 1 MeV. Another approach, which is actually the origin of this method, is to measure the neutron high-energy tail produced by alpha knock-on energetic ions [20]. The neutron high-energy tail can potentially be measured using a high count rate neutron spectrometer, such as a magnetic proton recoil (MPR) spectrometer or bubble detectors.…”

Section: Confined Alpha Measurementmentioning

confidence: 99%

Overview of neutron and confined escaping alpha diagnostics planned for ITER

Sasao

Krasilnikov

Nishitani

et al. 2004

Plasma Phys. Control. Fusion

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Fusion product measurements planned for ITER are reviewed from the viewpoint of alpha particle-related physics studies. Recent advances in fusion plasma physics have extended the desirable measurement requirements to the megahertz region for neutron emission rate, better resolution of neutron profiles for the study of internal transport barriers (ITBs), etc. Employing threshold counters and/or scintillation detectors confers megahertz capability on neutron emission rate measurement. The changes in the neutron/alpha particle birth profile due to the formation of ITB and its deviation from uniformity on the magnetic flux surface can be measured by addition of eight viewing chords in an equatorial port plug and seven viewing chords from the divertor to the original radial neutron camera. On the other hand, it is still difficult to measure the distributions of confined and escaping alpha particles. Several proposals to resolve these difficulties are currently under investigation.

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Section: Confined Alpha Measurementmentioning

confidence: 99%

Overview of neutron and confined escaping alpha diagnostics planned for ITER

Sasao

Krasilnikov

Nishitani

et al. 2004

Plasma Phys. Control. Fusion

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“…[51]. The alpha knock on component is also included in this study [15]. The alpha knock on component originates from fuel ions heated by α particles created in an initial d+t reaction.…”

Section: Ion Cyclotron Resonance and Alpha Heated Plasmasmentioning

confidence: 99%

“…The covered momentum range is superficially limited by the hodoscope size but is ultimately limited by the spectrometer's ability to give the required performance over an extended momentum (energy) range. The MPR technique has been used at JET since the late 90's [15,16,17] providing information on practically all plasma parameters accessible by neutron spectrometry.…”

Section: Magnetic Proton Recoil Techniquementioning

confidence: 99%

Evaluation of neutron spectrometer techniques for ITER using synthetic data

Sundén

Ballabio

Cecconello

et al. 2013

Nuclear Instruments and Methods in Physics Research Section A:

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A neutron spectrometer at ITER is expected to provide estimates of plasma parameters such as ion temperature, T i , fuel ion ratio, n t /n d , and Q thermal /Q tot , with 10-20% precision at a time resolution, Δt, of at least 100 ms. The present paper describes a method for evaluating different neutron spectroscopy techniques based on their instrumental response functions and synthetic measurement data. We include five different neutron spectrometric techniques with realistic response functions, based on simulations and measurements where available. The techniques are magnetic proton recoil, thin-foil proton recoil, gamma discriminating organic scintillator, diamond and time-of-flight. The reference position and line of sight of a high resolution neutron spectrometer on ITER are used in the study. ITER plasma conditions are simulated for realistic operating scenarios. The ITER conditions evaluated are beam and radio frequency heated and thermal deuterium-tritium plasmas. Results are given for each technique in terms of the estimated time resolution at which the parameter determination can be made within the required precision (here 10% for T i and the relative intensities of NB and RF emission components). It is shown that under the assumptions made, the thin-foil techniques out-perform the other spectroscopy techniques in practically all measurement situations. For thermal conditions, the range of achieved Δt in the determination of T i varies in time scales from ms (for the magnetic and thin-foil proton recoil) to s (for gamma discriminating organic scintillator).

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“…The theory is predicated on the assumption that multiple small angle collisions predominate. In dense plasmas, subdominant terms are no longer negligible; 3 also, nuclear large-energy transfer events 4 or ''knock-on'' collisions [5][6][7] can be important, particularly in sparsely populated portions of the distribution function. More fundamentally, the standard theory uses an ad hoc cutoff at small angles to represent the effect of Debye shielding.…”

Section: Introductionmentioning

confidence: 99%

Accurate measurements of the pitch-angle scattering of beam ions

Heidbrink

2002

Physics of Plasmas

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The pitch-angle scattering rate of a dilute population of 75 keV deuterium ions is measured in a well-diagnosed, relatively quiet, magnetically-confined deuterium plasma. Neutral particle diagnostics detect the fast-ion density in velocity space following a short 10 ms pulse of injected beam ions. The data are compared to the classical theory of diffusion in velocity space caused by many, small-angle, Coulomb-scattering events. Within uncertainties of Շ15%, the data confirm the classical theory.

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Observation of the Alpha Particle “Knock-On” Neutron Emission from Magnetically Confined DT Fusion Plasmas

Cited by 103 publications

References 14 publications

Overview of neutron and confined escaping alpha diagnostics planned for ITER

Overview of neutron and confined escaping alpha diagnostics planned for ITER

Evaluation of neutron spectrometer techniques for ITER using synthetic data

Accurate measurements of the pitch-angle scattering of beam ions

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