Short Repetitive Pulses of 50–75 kV Applied to Plasma Immersion Implantation of Aerospace Materials

Abstract

High-energy plasma immersion ion implantation (PIII) in the range of 50-100 keV is an interesting alternative of surface modification technique to more commonly investigated beam processing of materials in such energies. A stacked Blumlein (SB) technique was used to reach high-voltage pulses of 30 to 100 kV, with much cheaper and electronically simpler configuration compared to a hard-tube (HT) system previously used by another PIII group. The reason is because Blumlein systems employ cheaper thyratrons with higher current capabilities compared to HT tetrodes. Although HT modulators provide higher retained peak dose and variable pulse duration, Blumlein pulsers are preferable for low-cost systems with lower dose and high-energy implantation. The disadvantages of Blumlein systems are their fixed pulse duration and lower repetition rate (<300 Hz) during operation regime. In this paper, PIII results obtained for SB operations between 50 and 75 kV will be discussed using an improved vacuum system and a proper high-voltage feed-through of 75 kV. High-energy (up to 75 keV) short (1.2 mus) repetitive (100 Hz) pulses were delivered to produce the plasma and carry out nitrogen ion implantation in the high-voltage glow-discharge mode. Al7475, Al5052, Ti6Al4V alloys, and ultrahigh-molecular-weight polyethylene polymer are materials of great interest to the aerospace field which are being treated by this high-energy PIII technique.