High-voltage pulse rise time decreasing using transmission coaxial and spiral lines with ferrite

This article presents the results of a study of the formation of a short rise time of a powerful nanosecond 410 kV pulse. Ferrite filled coaxial transmission lines with standard inner conductor and construction in the form of a spiral are designed. The sharpening of the pulse occurs due to the appearance of an electromagnetic shock wave in the ferrite. The value of the rise time at the level of 0.1 - 0.9 has been decreased from 4.5 to 2.5 ns.

Simulating Plasma Formation in Pores under Short Electric Pulses for Plasma Pulse Geo Drilling (PPGD)

Plasma Pulse Geo Drilling (PPGD) is a contact-less drilling technique, where an electric discharge across a rock sample causes the rock to fracture. Experimental results have shown PPGD drilling operations are successful if certain electrode spacings, pulse voltages, and pulse rise times are given. However, the underlying physics of the electric breakdown within the rock, which cause damage in the process, are still poorly understood. This study presents a novel methodology to numerically study plasma generation for electric pulses between 200 and 500 kV in rock pores with a width between 10 and 100 μm. We further investigate whether the pressure increase, induced by the plasma generation, is sufficient to cause rock fracturing, which is indicative of the onset of drilling success. We find that rock fracturing occurs in simulations with a 100 μm pore size and an imposed pulse voltage of approximately 400 kV. Furthermore, pulses with voltages lower than 400 kV induce damage near the electrodes, which expands from pulse to pulse, and eventually, rock fracturing occurs. Additionally, we find that the likelihood for fracturing increases with increasing pore voltage drop, which increases with pore size, electric pulse voltage, and rock effective relative permittivity while being inversely proportional to the rock porosity and pulse rise time.

A study of high transient voltage unit realization uncertainty

The problem of metrological support of high-voltage pulse generators with subnanosecond rise time, as well as pulse voltage dividers used in power engineering, aviation and rocket-space industries, has been solved. As a result of the modernization of the State primary special standard of transient electric and magnetic field strengths units with a pulse rise time in the range of 0.1–10.0 ns GET 148-2013, a mode of realization a unit of high transient electric voltage with a minimum pulse rise time of 100 ps was implemented. Uncertainties of high transient electric voltage unit realization obtained by numerical simulations using the Monte Carlo method, as well as in accordance with the Guide to the Expression of Uncertainty of Measurement (GUM), are estimated. Also, the error of a unit realization was estimated in accordance with GOST 8.381-2009 “GSI. Standards. Methods to Express Accuracy”.

A thermoelastic microelongated layer immersed in an infinite fluid and subjected to laser pulse heating

The present investigation deals with the twodimensional deformation because of laser pulse heating in a thermoelastic microelongated layer with a thickness of 2d, which is immersed in an infinite nonviscous fluid. Normal mode analysis technique is applied to obtain the analytic expressions for displacement component, force stress, temperature distribution, and microelongation. The effect of elongation and laser pulse rise time on the derived components have been depicted graphically.