Mathematical Simulation of a High-Frequency Low-Pressure Discharge with Gas Injection in Non-Local Approximation: Electro- and Plasmadynamics

The electro- and plasmadynamic parameters of a high-frequency discharge at a low pressure (13.3–200 Pa) with a gas blowing-through are investigated in a nonlocal approximation. A discharge in a cylindrical discharge tube in a medium of argon is considered. The flow at the beginning of the discharge tube occurs in the regime of a continuous medium, whereas in the region of a plasma bunch and further downstream the flow regime changes to a freemolecular one. In this connection, a hybrid mathematical model is constructed that includes the Boltzmann equation for a neutral gas and the balance equations of the concentration and energy of electrons in the continuous medium approximation. The equations for the plasma particles are supplemented by the Maxwell equations transformed into the equations of telegraphy in the high-frequency electric intensity. The results of calculations of the electric intensity, concentration of electrons, and of electron temperature in the discharge tube are presented. It is shown that account for the nonlocality is an essential factor in simulating the high-frequency inductive discharge with gas injection ensuring effective transfer of charged particles from the field of their generation to the working chamber

Electrolyte-plasma product treatment

© 2020 Published under licence by IOP Publishing Ltd. The low-temperature plasma of direct current electric discharges in the process of surface treatment of a product investigated. The types and forms of discharge burning investigated. The electric parameters of the discharge, oscillations of the current and voltage of the discharge, the power invested in the discharge investigated. The temperature distributions of the electrodes in the combustion zone of the discharge investigated. The composition of the discharge plasma, the electron concentration, and the rotational and vibrational temperatures of the heavy components are studied. The micro relief of the surface of the product studied before and after electrolyte-plasma treatment

Calculation of conditions for maintaining an ICRF-plasma using a self-consistent model

The article proposes a new approach to calculating the strength of the magnetic field on the inner wall of the discharge chamber, which is necessary to maintain a steady state of a low-pressure ICRF discharge. The model is treate as a nonlinear eigenproblem. The influence of the third type boundary conditions for electron density as well as and the nonlinear boundary conditions for electrical strength is considered. This approach makes it possible solving two problems of designing ICRF plasma torches: for a given electron density in the discharge find the magnetic field strength that ensures the maintenance of the discharge, or, conversely, at a given magnetic field strength, determine the value of the electron density that can be created in the discharge. In addition, the radial distributions of the electric and magnetic fields and the electron concentration can be determined

Study of RF plasma flow at low pressure: Electron temperature influence

© 2020 Published under licence by IOP Publishing Ltd. A mathematical model of low-pressure RF plasma flow taking into consideration electron temperature influence is presented. Results of calculations of carrier gas velocity, pressure and temperature as well as electron density and electron temperature in plasma flow are showed. Influence of electric field on electron temperature and plasma flow is analyzed

Experimental installation to study the RF plasma flow at low pressures with experiment data synchronization

© 2020 Published under licence by IOP Publishing Ltd. A diagram and description of an experimental setup for studying the properties of a stream of RF plasma at low pressure are presented. The setup is equipped with diagnostic devices that record the temperature, volt-ampere characteristics, and pressure in the chamber

Histone deacetylase inhibitors cause TP53-dependent induction of p21/Waf1 in tumor cells with TP53 mutations

The p21/Waf1 protein is one of the main regulators of cell cycle arrest and one of the best-known transcriptional targets of the TP53 protein. Here, we demonstrated that there is activation of expression of the p21/Waf1 gene when the cells were treated with sodium butyrate (NaBu), which is a natural histone deacetylase inhibitor, and investigated whether this phenomenon depends on the presence of a functionally active TP53 protein. For this purpose, we compared the effect of NaBu treatment of human cell lines with different TP53 mutation profiles, including wild-type TP53, single nucleotide substitutions, and the complete absence of the TP53 gene. NaBu activated the TP53 protein via hyperacetylation at the lysine residue K382, without significant changes in the level of protein expression. Western blotting showed that the addition of NaBu triggers a significant increase in the p21/Waf1 protein level in both TP53 wild-type cells and in cells with single nucleotide substitutions in the central DNA-binding core domain (DBD) of the TP53 protein. At the same time, no p21/Waf1 protein induction was observed in cells with complete deletion of the TP53 gene. However, NaBu was not able to induce p21/Waf1 production when the expression of TP53 was transiently knocked down by the p53 siRNA. Overall, our results suggest that NaBu-dependent induction of p21/Waf1 does require the presence of TP53 protein, but, unexpectedly, it can occur regardless of mutational changes in the domain responsible for the TP53 binding to DNA. One possible explanations is that NaBu increases the level of TP53 acetylation and the modified protein is able to establish a new network of protein–protein interactions or trigger conformational changes affecting the TP53-dependent transcriptional machinery even when its DNA binding ability is impaired