Toroidal plasma conditions where the p-11B fusion Lawson criterion could be eased

Abstract

We examine the theoretical conditions in which the Lawson ignition criterion for p-11B fusion in a magnetized toroidal plasma can be reduced substantially. It is determined that a velocity differential between the protons and the boron ions of the order of the plasma sound speed (Mach number of 1 or 2 at a plasma temperature of ~102 keV) could raise the p-11B fusion reaction rate to ~2x10-22 m3/s or ~6x10-22 m^3/s, respectively, from the ~1x10-22 m3/s level in a static plasma. The Lawson triple product (ni τE Ti) required for ignition can thereby be reduced to as low as ~1023 m-3 s keV, which is one order of magnitude above the ITER requirement for D-T burn. Since order-unity Mach numbers in velocity differentials between deuterons and impurity carbon ions have been maintained in tokamak plasmas under excellent confinement conditions, similar levels of velocity differentials between protons and minority boron-11 ions could in principle be maintained also. A theoretical possibility of achieving p-11B fusion ignition in a toroidal plasma of ~102 keV in ion temperature is hereby presented. Similar p-13C plasmas, for example, will introduce a possibility of measuring the CNO fusion chain reaction rates in a laboratory.

Fusion reactivities with drift bi-Maxwellian ion velocity distributions

“…Thus, the impact of the distribution function on the fusion reactivity is crucial in the study of p-B11 fusion. Previous studies [36,37] of p-B11 fusion with beam fusion should be carefully examined, as they treated drift energy oversimplified. A more practical study would keep the total energy (n 1 E k1 + n 2 E k2 ) constant, which could provide more insight into the best choice for T ∥,⊥j and v dj , and lead to further results based on those shown in section 3.…”

Solenoid-free current drive via ECRH in EXL-50 spherical torus plasmas

“…CS-free ECRH and current drive has been tested in several earlier ST devices (CDX-U [10], LATE [11][12][13][14][15], TST-2 [16][17], MAST [18][19], and QUEST [20][21][22][23][24][25][26]). A toroidal current of 1.05 kA was generated using about 8 kW of ECRH power on CDX-U [9], proving the possibility of current start-up by ECRH alone. Later, a 7kA plasma current was generated by about 30kW ECRH in LATE [11][12].…”

“…The original physics concept and principle of the ENN Spherical Torus with a major radius 50 cm (EXL-50) in Energy iNNovation (ENN) Science and Technology Development Co. was recently proposed by Peng [9]. One of the key EXL-50 experimental goals is to test the efficacy of electron cyclotron resonance heating (ECRH) and current drive in the absence of an CS magnet.…”