Determinations of plasma density and decay time in the hollow cathode discharge by microwave transmission

The microwave （MW） transmission method is employed to measure both the plasma density and the plasma decay time in the hollow cathode discharge （HCD） in argon at low pressure. The plasma density in DC-driven or pulsed HCD is on the order of 1012 cm-3, which can block the X-band MW effectively. In the case of pulsed HCD, the MW transmittance shows the same waveform as the pulsed current during the rising edge if the driving frequency is low, but with a longer delay during the falling edge. The MW transmittance reaches a constant low level when the driving frequency is high enough. The plasma decay time in the HCD system is measured to be about 100 μs around a pressure of 120 Pa. The ambipolar diffusion is considered to be the major mechanism in the decay process.

Circle Points Discharge Tube Current Controller

Circle points discharge tube current controller is a new type device to limit the output of high voltage discharge current. Circle points uniform corona discharge to form air ionization current in the discharge tube. On the outside, even if the discharge electrode is spark discharging or the two discharge electrodes are short circuited, the air ionization current in the tube remains within a stable range, and there is no spark discharge. In this case, when the discharge current only increases slightly, the requirement to limited current is obtained. By installing the controller at a discharge pole with a small power but high voltage supply, we can realize the shift between the continuous spark line discharge and corona discharge. This provides a new simple device for spark discharge research and is a supplement to the Townsend discharge experiment.

High discharged energy density of polymer nanocomposites induced by Nd-doped BaTiO_(3)nanoparticles

A flexible polymer nanocomposite has been developed via introducing Nd-doped BaTiO_(3)nanoparticles into the poly(vinylidene fluoride).This nanocomposite delivers a discharged energy density up to 12.5 J/cm^(3)under an electric field of 420 kV/mmwith only a small loading of 1 vol.%Nd-BaTiO_(3).High discharged energy density,mechanical flexibility,light weight,ease fabrication and low cost makes it attractive for advanced microelectronics and electrical power systems.Our results demonstrate that ceramics with giant dielectric permittivity as viable fillers for polymer nanocomposite dielectrics with higher energy density.

High energy storage performance for dielectric film capacitors by designing 1D SrTiO_(3)@SiO_(2) nanofillers

The development of advanced dielectric film materials with high energy storage performance is of critical significance for pulsed power capacitor applications.Nevertheless,the low discharged energy density(Ue)of current dielectric film material restricts their further application.In this work,core-shell structured SrTiO_(3)@SiO_(2) nanowires(ST@SiO_(2) NWs)fillers are fabricated based on interface engineering for high Ue.The optimized SiO2 insulating layer could effectively confine the mobility of space charge carriers in the interfacial zone between ST NWs and thick SiO2 insulating layer,thus reducing the interfacial polarization between the interface of nanofillers/polymer,which could be used to optimize the electric field strength and electric displacement of the corresponding nanocomposite.As a result,this nanocomposite film simultaneously exhibits enhanced maximum applied electric field(Emax)and(Dmax-Pr)values,thus releasing an ultrahigh discharged energy density of 14.7 J/cm^(3) at 390 MV/m,which is 99%higher than that of the conventional ST/P(VDF-CTFE)(without SiO2 coating)nanocomposite,and it is almost 2.5 times that of pure P(VDF-CTFE).This work demonstrates the superiority of the core-shell structured paraelectric nanowire in enhancing the energy storage performance of dielectric film capacitors,which is expected to guide the design of advanced energy-storage nanocomposites.