Methods for suppressing plasma inhomogeneity in the multi-cusp single driver negative ion source for neutral beam injector

Methods for suppressing plasma inhomogeneity in the multi-cusp single-driver negative ion source for neutral beam injector were investigated via a 2.5D MCC-particle-in-cell model in KARAT code, accompanied by a 2D hydrodynamic model of inductively coupled plasma. In the basic configuration of a negative ion source, plasma density parameters near PG are asymmetry A = 0.24, coefficient of variation CV = 0.74, and average value of electron density ne = 2.3 × 1017 m−3. The results of magnetic field alignment are A ≈ 0, CV = 0.64, and ne = 1.8 × 1017 m−3. The results of diamagnetic ∇p drift flow redirection are A = 0.20, CV = 0.64, and ne = 2.1 × 1017 m−3. The results of blocking plasma drift via thin barrier plates are A = 0.16, CV = 0.74, and ne = 2.3 × 1017 m−3. Different methods for plasma inhomogeneity suppression have been successfully evaluated, and useful negative ion source configurations have been found.