Discharge characteristics of the DUHOCAMIS with a high magnetic bottle-shaped field

Abstract

For the purpose to produce high intensity, multiply charged metal ion beams, the DUHOCAMIS (dual hollow cathode ion source for metal ions) was derived from the hot cathode Penning ion source combined with the hollow cathode sputtering experiments in 2007. It was interesting to investigate the behavior of this discharge geometry in a stronger magnetic bottle-shaped field. So a new test bench for DUHOCAMIS with a high magnetic bottle-shaped field up to 0.6 T has been set up at Peking University, on which have been made primary experiments in connection with discharge characteristics of the source. The experiments with magnetic fields from 0.13 T to 0.52 T have shown that the magnetic flux densities are very sensitive to the discharge behavior: discharge curves and ion spectra. It has been found that the slope of discharge curves in a very wide range can be controlled by changing the magnetic field as well as regulated by adjusting cathode heating power. On the other hand, by comparison of discharge curves between dual hollow cathode discharge (DHCD) mode and PIG discharge mode, it was found a much stronger magnetic effect occurred on DHCD mode. In this paper, the new test bench with ion source structure is described in detail; and main experimental results are presented and discussed, including the effects of cathode heating power and magnetic flux density on discharge characteristics, also the ion spectra. The effects of the magnetic field on the source operating are emphasized, and a unique behavior of the DUHOCAMIS operating in the high magnetic field is expected and discussed especially.

The Study on Failure Mechanism of 3D Cracked Rock Mass under Fissure Water Pressure

“…The mechanical parameters of specimens and cracks are shown in Table 1. An improved elasto-brittle model [4] is adopted in the numerical modeling with FLAC3D. For reduction of the mechanical parameters for damaged elements, the residual shear strength is taken as 25% of the initial value when only shear failure occurs; the tensile strength and cohesion is reduced to about 5% of the initial values when tensile failure occurs; the friction angle remains unchanged, the bulk modulus is reduced to 50% and shear modulus is reduced to 10% of the initial values for any type of failure.…”