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Description
Recent beam phase space measurement of the J-PARC negative hydrogen ion ($\text{H}^-$ ion) source shows that the extracted beam involves several components: beam core, diverging halo, converging halo, and asymmetric components [1]. As the beam components except the core lead to beam losses after accelerating in the linac cavities, understanding of the halo formation is an important task. A 3D electrostatic Particle-In-Cell (ES-PIC) simulation [2] is applied to the J-PARC ion source to clarify the relation between the beam components and the $\text{H}^-$ production processes in the plasma. The $\text{H}^-$ ions in the model are produced in three different processes: (1) volume production, (2) surface production by $\text{H}^0$ atoms, and (3) surface production by protons. The transport of the $\text{H}^-$ ions is calculated and associated with the beam components after being extracted from the ion source.
[1] T. Shibata, et al., AIP Conf. Proc. 2373, 050002 (2021).
[2] T. Shibata, et al., J. Phys.: Conf. Ser. 2743, 012007 (2024).
