Relativistic calculation of fusion product spectra for thermonuclear plasmas

Abstract

The first three moments of the energy distributions of products from fusion reactions in thermonuclear plasmas with Maxwellian ion velocity distributions are determined analytically. Relativistic kinematics is used allowing the desired accuracy to be reached, which is 2 to 3 orders of magnitude better than previous analytical results. In particular, neutron spectra of the reactions D(d,n)3He and D(t,n)α for plasma ion temperatures 0 < Ti < 100 keV are studied for which the results are also given in tabulated form with interpolation formulas for the purpose of practical use. The neutron energy distributions are also calculated with numerical methods, in order to assess the analytical results. High accuracy calculations are motivated by the crucial role that neutron measurements are envisaged to play in the next step fusion experiments on burning plasmas, which are also discussed.

Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility

“…In this paper we focus on the ion "temperatures" from a more extensive set of experiments than previously published [2] and conclude that the fuel assembly during burn in layered DT implosions is not well described by detailed one-dimensional (1D) physics models and simulations. The leading hypothesis for the observed discrepancy between the data and the 1D description is significant disordered motion and the highly 3D nature of the assembly at burn.For a homogeneous stationary DT plasma in thermal equilibrium at ion temperature T thermal , the variance of the * Corresponding author: gatu@psfc.mit.edu DT neutron spectrum (in units of neutron energy) is given bywhere E n is the neutron energy and m n and m α are the fusion product masses [17][18][19][20]. This has been traditionally used to infer T ion [21,22].…”

“…For the implosions studied here, the apparent T ion is inferred (using the formalism developed in Ref. [20]) from the variance of the neutron spectrum produced in a plasma known to be nonhomogeneous. In this scenario, one has to consider what impact fuel elements at different T thermal (and possibly different σ 2 v ) have on the primary neutron spectrum.…”

“…where E n is the neutron energy and m n and m α are the fusion product masses [17][18][19][20]. This has been traditionally used to infer T ion [21,22].…”

“…For the implosions studied here, the apparent T ion is inferred (using the formalism developed in Ref. [20]) from the variance of the neutron spectrum produced in a plasma known to be nonhomogeneous. In this scenario, one has to consider what impact fuel elements at different T thermal (and possibly different σ The data points come from cryogenically layered NIF DT implosions, with HiFoot-driven 195-μm CH ablator shots in green, 175-μm CH ablator shots in blue, 165-μm CH ablator shots in pink, HDC shots in purple, and shots driven with an adiabat-shaped laser pulse in orange.…”

Evaluation of neutron spectrometer techniques for ITER using synthetic data

“…In this study, a fixed shape has been used for the beam-thermal component, assuming the reference LOS of the instrument as described in Section 1, a beam injection energy of 1 MeV, an injection angle of the deuteron beam of 30° and an electron density of 10 20 [47]. The neutron emission spectrum from the beam-thermal component under these conditions has been modelled with the Monte Carlo code CONTROLROOM [48], and is shown in Figure 10. …”