Study of fusion regimes in an inertial electrostatic confinement device using the new eclipse disk diagnostic

Abstract

New diagnostics are required to understand the physics operation of an inertial electrostatic confinement (IEC) device. In an attempt to understand the fusion source regimes within the IEC device, a new diagnostic called the eclipse disk has been introduced. This diagnostic was used to exploit the byproduct protons’ energy difference between the deuterium-deuterium (D–D) and deuterium—an isotope of helium with two protons and one neutron (D–He3) reactions to study the contributions of the protons generated from various source regimes. These source regimes are divided into five categories namely: converged core, embedded, beam background, volume, and wall-surface sources. The eclipse disk diagnostic has provided the first confirmed evidence that D–He3 reactions are predominantly embedded reactions. It has been observed that at the present operating power levels (6–10kW) most of the D–D reactions occur in the volume of the chamber caused by the charge exchanged neutrals, and the converged core contribution is significant only for D–D reactions. Since the branching ratio for the proton and neutron generation in a D–D fusion reaction is ∼50%, it is inferred that the proton to neutron count ratio is a better parameter to monitor than either proton or neutron counts measured alone while studying the source regimes. This parameter may also be used for studying the potential wells within the cathode grid.