Effects of nuclear elastic scattering on ignition and thermal instability characteristics of D-D fusion reactor plasmas

Abstract

Nuclear elastic scattering is included in the analysis of ignition condition and thermal instability in pure and catalysed D-D fusion reactor plasmas. Nuclear-elastic-scattering events take place, to some extent, during the slowing-down of energetic fusion products and enhance the heating of the background ions. The inclusion of this effect relaxes the minimum of the confinement requirement for self-sustained D-D plasmas by about 15%. It enhances, however, the thermal instability of the plasma, leading to an increase in the critical temperature.

A Method of Knock-on Tail Observation Accounting Temperature Fluctuation Using ⁶Li+T/D+T Reaction in Deuterium Plasma

“…In this manner, the previously proposed method [3,8,9] can prove the presence of a knock-on tail by capturing the quantitative changes of these reaction rates. Although the change in neutron generation rate from the D(d, n) 3 He reaction is smaller than that change in γ-ray generation rate from the 6 Li(d, pγ) 7 Li and 6 Li(d, nγ) 7 Be reactions due to a knock-on tail formation, the higher emission rate from the D(d, n) 3 He reaction can still be expected than that γ-ray generation rate from the 6 Li(d, pγ) 7 Li and 6 Li(d, nγ) 7 Be reactions. The experiment using the proposed method for observing a knock-on tail has been projected on the Large Helical Device (LHD) at National Institute for Fusion Science.…”

“…The nonMaxwellian components in the velocity distribution functions via NES are referred to as a "knock-on tail." A knock-on tail has various effects on plasmas, e.g., reaction rate variations [3], spectrum modification of emission particles due to nuclear reactions [4], and ion-heating enhancement [5,6]. It is expected that a knock-on tail would be utilized for diagnosing fusion reactors [7].…”

“…This method employed the γ-raygenerating and neutron-generating nuclear reactions, such as 6 Li(d, pγ) 7 Li, 6 Li(d, nγ) 7 Be, and D(d, n) 3 He, occurring in a proton-beam-injected deuterium plasma admixed with a small amount of 6 Li. By injecting a high-energy proton beam into a deuterium plasma, the NES between protons and deuterons causes the formation of a knock-on tail in the high-energy region of the deuteron distribution function.…”

“…The following reactions are written as 6 Li(d, nγ) 7 Be, 6 Li(d, pγ) 7 Li, 6 Li(t, dγ) 7 Li, 6 Li(t, pγ) 8 Li, D(d, n) 3 He, D(d, p)T, and T(d, n) 4 He respectively. The cross sections of reactions (1), (2), (5), and (6) are shown in Fig.…”

“…The cross sections of reactions (1), (2), and (5) are employed for observing a knock-on tail. Because the 6 Li(d, nγ) 7 Be reaction, whose γ-ray energy is 0.429 MeV, and the 6 Li(d, pγ) 7 Li reaction, whose γ-ray energy is 0.478 MeV, have a reaction threshold, a rapid increase in the reaction rates can be expected by a knockon tail formation in the deuteron distribution function. In this manner, the previously proposed method [3,8,9] can prove the presence of a knock-on tail by capturing the quantitative changes of these reaction rates.…”