Generation and transportation of high-intensity pulsed ion beam at varying background pressures

Abstract

High-intensity pulsed ion beam (HIPIB) technology is developed as an advanced manufacturing method for components with improved wear, corrosion and/or fatigue performance, etc. Robust HIPIB equipment with stable repetitive operation, long-lifetime, and easy maintenance are desired for industrial applications, on which stability of ion beam parameters is critical to achieve consistent result of reproducibility. Here, magnetically insulated ion diodes (MIDs) as ion source with durable graphite anode are investigated in a simple self-magnetic field configuration under repetitive operation. Influence of background pressure on ion beam generation and transportation is emphasized since ion beam sources were intrinsically a vacuum-based system. Comparative experiments were conducted on two types of HIPIB equipment, that is, TEMP-6 and TEMP-4M, differing in vacuum packages where turbo-molecular pump or oil diffusion pump was used. Both the HIPIB equipments are operated on a bipolar pulse mode, that is, a first negative pulse of 150–200 kV with pulse duration 450–500 ns to generate anode plasma on explosive electron emission, and a second positive pulse of 200–250 kV with 120 ns to accelerate the ions. Ion beam energy density up to 8 J/cm2 is achievable using MIDs of geometrical focusing configuration, and the total energy, energy density distribution along cross-section, deflection and divergence, and charge neutralization of the ion beams are assessed under background pressures in a wide range of two orders of magnitude, that is, 1–100 mPa. No appreciable change in the parameters is observed up to 50 mPa, and merely a slight increase in the beam deflection from about ±3 mm to about ±4 mm at the focal point over 50 mPa. The stability of ion beam at the varied pressure is mainly facilitated by the higher pressure up to several Pa in anode–cathode gap during plasma generation and good neutralizing effect for ion beam transportation.

Diagnostics of Pulsed Beams of Electrons, Ions, and Atoms (Review)

“…For an HPIB energy density below 10 J/cm 2 and a pulse duration of 150 ns, the ion concentration is at most 10 13 cm -3 ; therefore, the probability of their collisions (and velocity changes) in the drift region is low. The divergence of ions in the HPIB is 5°-8° [43].…”

Investigation of the characteristics of an intense ion beam propagated outside the diode

“…Geometric focusing has been realized in the intense ion diodes of different types [1][2][3][4][5][6] for the formation and transportation of ion beams. This allows increasing the densities of the current and energy of the ion beam in the focus area by several times.…”