A pulse current generator for dense plasma focus

A pulse current generator applied in a type of high-yield intense pulsed neutron source, the Dense Plasma Focus (DPF), is designed and developed in this paper. There are three key components in this generator. Each group of capacitors and switches is integrative to meet the DPF's requirements of low circuit inductance. A coaxial multi-channel switch is developed to solve the problems of the switch inductance, the jitter and the electrode erosion. A kind of sectorial plate transmission line is adopted to transfer the high pulse current from the capacitors to the DPF. The following technical parameters of the generator were achieved on dummy load: output current amplitude of ∼560 kA when primary capacitors are charged with 22 kV.

Stabilization Methods in the Submerged Arc Discharge Synthesis of Carbon Nanostructures

Many papers, in which the submerged arc discharge (SAD) method in nanoparticle synthesis was used, reported similar operating parameters, but different electrode erosion rate values, different yields and purities of the obtained nanostructures, and a different sort of contaminants present in the synthesis. Analyzing these articles, we found insufficient attention to ensure the arc power stability, which is a key factor guaranteeing the product homogeneity and quality. This paper presents an analysis of different control strategies, remarks their advantages and drawbacks, and proposes the most appropriate technique to be used in SAD. The most appropriate technique is proposed from the SAD stabilization method analysis.

The discharge initiation in vacuum gap by moderate intensity optical range radiation

The hypothesis of discharge initiation in vacuum gap by optical range radiation based on previously obtained experimental data. During the laser pulse interaction with electrode erosion products the glow discharge has ignited. In result of ioniza-tion-overheating instability the discharge has had current channel contraction and has transferred to arc. The dependences of material of target thermo dynamical parameters on the minimal and threshold laser pulse energy have demonstrated. The threshold laser pulse energy – the energy which enough to effective impact on the laser plasma.

Overview of key technologies of high power arc heater

Arc-heated facilties play an important role in ground tests, such as appraisal of thermal protection systems(TPS) of various hypersonic vehicles and simulation of a high Mach scramjet's thermal structure and combustion chamber performance. This paper analyzes the requirements for developing a high power arc heater. Key technologies for developing it include high power, high voltage, high enthalpy and electrode erosion in high currents. Finally, the paper proposes the related ideas and methods for these key technologies, providing theoretical references for China's development of a super-high power arc heater.

A Computational Study of the Thermodynamic Conditions Leading to Autoignition in Nanosecond Pulsed Discharges

Nanosecond pulsed discharges have attracted the attention of engine manufacturers due to the possibility of attaining distributed ignition sites that accelerate burn rates while resulting in very little electrode erosion . Multidimensional modeling tools currently capture the electrical structure of such discharges accurately, but resolving the chemical structure remains a challenging problem owing to the disparity of time-scales in streamer propagation (nanoseconds) and ignition phenomena (microseconds). The purpose of this study is to extend multidimensional results towards resolving the chemical structure in the wake of streamers (or the afterglow) by using a batch reactor model. This can afford the use of very detailed chemical kinetic information. The full non-equilibrium nature of the electrons is taken into account, along with fast gas heating, shock wave propagation, and thermal diffusion. The results shed light on ignition phenomena brought about by such discharges.