Investigation On Plasma Load Characteristic And Pulsed Bias Power Supply Of Arc Ion Plating

Pulsed bias arc ion plating (PBAIP) is an important ion plating technology, which developed very fast recently. But there are some problems desiderating to solve. This paper investigated on several problems of PBAIP, including its plasma load characteristic, pulsed bias power supply, the matching between pulsed bias power supply and plasma load of arc ion plating (AIP), and the "green" design of pulsed bias power supply. The research work of this paper is very important to increase the arts and crafts level of PBAIP.1. Investigation on plasma load characteristic of arc ion platingBased on plasma sheath theory, the electrotechnic theory, numerical simulation, and the experimental research work, the macroscopical circuit model of plasma load of arc ion plating is set up. The obtained result is that the plasma load of arc ion plating, formed by plasma sheath, is essentially capacitive, and can be approximated to a unit of a capacitor and a resistor in parallel.By researching on the evolutive process of plasma sheath of AIP with pulsed bias voltage, the analytical equation of the process is obtained. The analytical result shows that the period of forming stable plasma sheath of AIP is much less than that of beam ion plating, as well as the sheath thickness and its changing range. The expanding of the plasma sheath of AIP is almost following the change of pulsed-bias in real time.Based on the feature of the evolutive process of the plasma sheath of AIP, the time variable S(t), the thickness of plasma sheath of AIP, is time averaged andbecome S(t), average thickness; the time variable C(t), equivalent capacitance of the plasma sheath of AIP, is equivalent to a variable which is independent on time and dependent on the scope of pulsed bias and microcosmic parameters of plasma, such as the electron temperature of plasma etc. The relationship of the circuit model of AIP with the plasma parameters is founded. Based on the above work and according to the diagnosis results of plasma parameters of AIP using Langmuir probe, the scope of the equivalent capacitor of plasma sheath is obtained.It is validated by experiments, simulation and theoretic calculation that the macroscopical circuit model of plasma load of AIP and its relationship with microcosmic parameters of plasma is effective.The above research work provided theoretic and technical support for solving the problem of matching between pulsed bias power supply and plasma load of AIP and interrelated problem of arts and crafts of AIP.2. Investigation on pulsed bias power supply of AIPConsidering the plasma load characteristic of AIP, the paper developed a solid switching pulsed-bias power supply, having performance as following: the scope of voltage 50-1500V, frequency 5~40kHz, duty cycle 5%~40%, and power 15kW. The features of the power supply are as follows: (1) designed a high voltage pulse forming circuit with cascade structure, which making the power supply having high performance of expansion and extension, and is benefit to modularization; (2) developed a semiconductor power switching module having functions of earth protection and switching. This module supplied a gap of semiconductor power switching module in existence having no function of earth protection, and is benefit to increase safety of power supply; (3) designed a new duty cycle measuring circuit based on differential voltage amplifier, which can measure duty cycle of pulsed-bias digitally, is given to solve problems of the exist.Based on circuit theory and Lap lace transform, transfer function and step signal response characteristic of load loop of AIP is obtained. It provides a solution not only for the problem that pulse voltage oscillates in the load of plating, but also for the design of matching circuit. Aiming at the load characteristics of arc ion plating, designed a matching circuit consists of inductive (Z) branch in parallel with a series arm of a resistor (i?) and a capacitor (C). Also, frequency response characteristics of load loop including the matching circuit is obtained. In the effective spectrum of pulse voltage, the frequency response characteristics can be approximated to an undistorted system. The simulation and experimental results shows that the matching circuit is effective.The noise spectrum of pulsed-bias power supply is mainly below 2MHz according to predictive and actual measurement results. Based on the analysis using electromagnetic field theory, the disturbance of pulsed-bias power is near-field interference. The electromagnetic field produced by current carrying conductor in the power supply is mainly high-impedance electrical field. The field intensity is...