Electron beam transport through a quadrupole electrostatic system is investigated by particle-in-cell simulation in the present work, where - at the advantage of easier experimental implementation - the analogous parabolic electrostatic potential replaces the usual neutralizing ion background of bounded plasma systems. Looking at the maximum transported current and the dynamical behavior dependence on the electron beam injection energy, we have found that for a partial neutralizing electrostatic potential (i) the transmitted current significantly increases in relation to other electrostatic devices, due mainly to two-dimensional effects, (ii) the occurrence of stable static solutions with the typical profile of unstable static solutions of the classical Pierce diode, and (iii) a new bifurcation sequence of the steady-state solutions, at which periodic virtual cathode oscillations turn into intermittent spiking oscillations, which ultimately evolve to stable oscillations when increasing the input energy of the injected electron beam.

The biggest advantage of plasma immersion ion implantation (PIII) is the capability of treating objects with irregular geometry without complex manipulation of the target holder. The effectiveness of this approach relies on the uniformity of the incident ion dose. Unfortunately, perfect dose uniformity is usually difficult to achieve when treating samples of complex shape. The problems arise from the non-uniform plasma density and expansion of plasma sheath. A particle-in-cell computer simulation is used to study the time-dependent evolution of the plasma sheath surrounding two-dimensional objects during process of plasma immersion ion implantation. Before starting the implantation phase, steady-state nitrogen plasma is established inside the simulation volume by using ionization of gas precursor with primary electrons. The plasma self-consistently evolves to a non-uniform density distribution, which is used as initial density distribution for the implantation phase. As a result, we can obtain a more realistic description of the plasma sheath expansion and dynamics. Ion current density on the target, average impact energy, and trajectories of the implanted ions were calculated for three geometrical shapes. Large deviations from the uniform dose distribution have been observed for targets with irregular shapes. In addition, effect of secondary electron emission has been included in our simulation and no qualitative modifications to the sheath dynamics have been noticed. However, the energetic secondary electrons change drastically the plasma net balance and also pose significant X-ray hazard. Finally, an axial magnetic field has been added to the calculations and the possibility for magnetic insulation of secondary electrons has been proven.

The treatment of surfaces by plasma immersion ion implantation requires pulsed power modulators to provide negative high voltage pulses. To achieve this requirement, we have developed three basic circuit configurations in our laboratory: pulse forming network (PFN), hard-tube pulser (HT) and Blumlein line. In this paper we discuss these three types of circuit topologies.As experimental results, first we present the voltage/current characteristic waveforms of PFN and HT pulsers in the PIII treatment of different materials (aluminum, silicon and stainless steel) as well we describe the surface characterization of the materials thereof treated.And finally,we show recent high voltage tests of a high voltage Blumlein pulser (150kV/300A/1mus) to be used in surface treatments of polymers and aluminum alloys.