Power balance and impurities in two-component, multiple-mirror reactors

Abstract

A multiple-mirror DT reactor with injected power supplied by a fast neutral D beam is considered, and the power-balance equations for the hot and warm components are solved. For a fixed mirror ratio M1 and fixed Q = fusion power/injected power, the warm- and hot-deuterium fractions, the warm temperature, and the injection energy are determined so as to minimize the plasma pressure-reactor length product p1L. The equilibrium hot-ion distribution and the energy transfer factors are found analytically from the Fokker-Planck equation. For Q = 2.8 and M1 = 3.3, it is found that the additional hot-component fusion reactions produce a 26% reduction in p1L, to 4 × 105 bar·m. The seeding of the plasma with low-Z impurities so as to reduce the axial power loss has also been considered. Using a corona equilibrium model and optimizing the impurity fraction, an additional 10% reduction in p1L is obtained.

A theoretical study of ICRF effects on multiple-mirror confinement

“…where boundary is given by sin 2 0LC = l/Rj. Evaluating the integral, (11) We can eliminate Gj between (10) and (11) and solve for nj. To account for the enhanced axial loss due to ambipolar effects, we must divide nj by 2.…”

“…Hence, the radial confinement time is determined by the ambipolar diffusion rate. Another way to enhance Coulomb scattering and shorten the system length is to add high-Z impurities to the plasma [11]. We have calculated the effect of these impurities on radial loss.…”

“…Multiple-mirror plasmas have been stabilized by using average-minimum-B fields [8,9], and high-0 operation has been achieved [10]. A number of reactor feasibility design studies have been made [11 -14], including wetwood burner operation [11], the effects of impurities [11], high-|3 radial diffusion [12], and economic optimizations [13,14]. These studies show that although the diffusive scaling of the axial loss is favourable, overall reactor lengths tend to be long, of the order of 400-1200 m.…”

Two-component, multiple-mirror reactor with depressed ion temperature

“…Two-component operation of a multiple-mirror reactor has recently been considered [12]. The re-circulating power in the reactor is supplied by a fast neutral deuterium beam.…”

“…The reactor model used here has been given previously [12]. The plasma density n, cross-sectional area A, cell length fi c and mirror ratio M are functions of axial position z, whereas the electron and triton temperatures are independent of z.…”