Method of nanosecond triggering for a sealed-off pseudospark switch

This paper describes a method of nanosecond triggering for the modified version of the commercially produced pseudospark switch TPI1-10k/50. The switch uses the trigger unit with the auxiliary glow discharge, and the proposed method is based on the principle of the current interception from the trigger unit to the grounded cathode cavity when the trigger pulse arrives. Different electric circuits for triggering have been investigated. In the circuit, where the so-called trigger resistor or the trigger inductance are available, in the whole range of hydrogen operating pressure, the range of the delay time of triggering corresponds to (80–100) ns with a jitter of (3–6) ns. In the electric circuit, where the trigger resistor is shortened, the delay time increases to about (110–140) ns. However, the jitter remains at approximately the same level.

Effect of a longitudinal magnetic field on the emission characteristics of a forevacuum plasma electron source based on a hollow cathode discharge

The effect of a longitudinal magnetic field on the emission characteristics of a forevacuum plasma electron source based on a discharge with a hollow cathode is studied. It is shown that, starting from a certain threshold value of the induction Bc, the magnetic field leads to a decrease in the plasma concentration on the axis of the cathode cavity. With a decrease in the diameter of the cathode cavity, the threshold value of Bc increases. On the other hand, the longitudinal magnetic field makes it possible to increase the diameter of the emission chan-nel, which contributes to a significant increase in the current of electron emission from the plasma. In this case, the degree of increase in the emission current is determined by the ge-ometry of the cathode cavity and the pressure of the working gas.

Influence of Electron Injection on the Characteristics of a Hollow Cathode Glow Discharge

The article presents the results of experimental studies of a glow discharge with a hollow cathode in helium and argon gases using an auxiliary discharge as an electron emitter. The authors proposed to make the electrode common for both discharges in the form of a cylindrical metal mesh. The advantage of this design is explained as follows. The connection between the discharges is carried out through holes in the grid with a geometric transparency of 0.2, which makes it possible not only to smoothly control the glow discharge current, but also to enhance the discharge current. Plasma is known to be one of the most efficient electron emitters; however, its use as a cathode in devices with a glow discharge at low gas pressures is complicated by the fact that a grid with small holes is required to separate the electron flow from the plasma, and it is impractical to use such a system in view of low mechanical strength of the grid Since the hollow cathode works effectively at low gas pressures, the release of an electron flux from the plasma of some auxiliary discharge is possible with much larger holes in the grid separating the plasma and the hollow cathode cavity. In this case, the grid can be made such that it can withstand sufficiently high thermal loads and can operate in typical discharge modes with a hollow cathode. The injection of electrons into the cathode cavity of the glow discharge changes the radial distribution of the glow intensity, the width of the cathode dark space, and other parameters of the plasma in the cathode cavity. The influence of electrons penetrating from the auxiliary discharge into the cathode cavity of the main discharge becomes significant when the current of these electrons is comparable to or exceeds the current of electrons leaving the grid cathode surface as a result of γ-processes. In parallel with the measurement of the optical and electrical characteristics of the hollow cathode glow discharge plasma, measurements of the electron concentration were carried out by the microwave sounding method. The entire current of the auxiliary discharge penetrates into the cavity of the main discharge; however, after acceleration in the cathode dark space, the electrons penetrating from the auxiliary discharge ionize gas atoms and noticeably increase the current of the main discharge. Additional ions formed due to the ionization of the gas by the injected electrons knock out new electrons from the cathode surface, which makes it possible to increase the discharge current.

INVESTIGATION OF GLOW DISCHARGE`S ENERGY PARAMETERS IN SMALL DIAMETER LONG TUBES

Urgency of the research. Cleaning the interior surfaces of the pipes is a mandatory operation, preceding the application of the coating using the methods of vacuum spraying. Significant disadvantages of traditionally applied methods of chemical and electrochemical purification of such surfaces conditioned the widespread use of plasma technologies based on low-temperature plasma glow discharge. Target setting. In particular, to date, the most common way to clean surfaces from various kinds of contaminants is ion spraying using a gas-discharge plasma of glow discharge. This cleaning method allows efficient removal of major types of contaminants such as fats, adsorbed water, gases, oxides, and allows processing surfaces of different configurations. Actual scientific researches and issues analysis. It is shown that the application of the glow discharge in the processes of purification and coating on the inner surface of pipes with a diameter of 56 mm in length 120 mm with the application of transverse magnetic field is shown. However, there are a number of difficulties, mainly related to the low productivity of the process, since the cleaning of the inner surface of such pipes was carried out for 60 minutes. Identification of unexplored parts of the general problem. It is possible to increase the processing efficiency by applying a glow discharge initiated in a hollow cathode. However, for today there are no data on the distribution of the concentration of charged particles inside the product, in which L >> d. The purpose of the work. The purpose of this work is a comparative analysis of stress-strain state (NDS) in the diffusion welding of compounds from heterogeneous materials, which occurs when heated in a normal glow discharge and glow discharge, initiated in a hollow cathode. The statement of basic materials. Using the probe method, the energy characteristics of the plasma of the glow discharge initiated in the hollow cathode were studied in relation to the conditions for the cleaning of the interior surfaces of long pipes of small diameter. It is shown that with a pressure in a gas-discharge chamber of 53 Pa and a discharge current of 0.075 A, a sufficiently dense plasma with a concentration of charged particles at the level of 1.6 ∙ 1010 cm-3 is formed in the investigated geometry of the cathode cavity, which is characterized by high heterogeneity in height of the cavity (40 ... 60 %). It is also shown that an effective mechanism of influence on the distribution of plasma in the middle of the cathode, in which L >> D is the change in the distance of the cathode anode, a decrease of which from 40 to 20 mm increases the uniformity to 15 ... 20 %, and the introduction of an additional anode ring in the discharge scheme - to 8 ... 10 %. Conclusions. It has been shown that the purification of the inner surface of long pipes of small diameter (in which L = 10D) by smoldering discharge using the effect of a hollow cathode is complicated by a number of factors, mainly due to the rather high heterogeneity of the distribution of the plasma inside the cathode cavity.

Breakdown Characteristics in Argon-Helium Mixtures Using an Improved Microcavity Hollow Cathode Emission Source

Improvements to the microcavity hollow cathode source are reported. These include a lower breakdown voltage and a larger operating range of fill-gas pressures of argon, helium, and mixtures of each. Data showing the effect of size, shape, and materials (copper and stainless steel) of the cathodes and anodes on the breakdown voltage are presented. The minimum discharge current required for the discharge to enter the cathode cavity is profoundly affected by the size of the cathode cavity.

Some Characteristics of the Hollow Cathode Discharge Source from Hollow Cathodes of Different Sizes and Shapes

The empirical evaluation of several types of two-piece hollow cathodes for the analysis of microsamples using both dc and pulsed discharge modes of the hollow cathode discharge is reported. The discharge parameters used are similar to those that have given good precision and sensitivity for microsamples in this laboratory. Both optical microscopy and scanning electron microscopy were used to follow sputtering effects on the cathode geometry. The sputtering patterns in the flat-bottom, two-piece cylindrical hollow cathode revealed directly the cathode dark space on the cathode cavity bottom. The temporal emission profiles from the spherical cathode cavity are similar to those observed in cylindrical cathode cavities. The temporal emission profile changes with the diameter of the cylindrical cathode cavity and is characteristic of the analyte.