Propagation of Short Electromagnetic Pulses through Nonconducting Media with Electric and Magnetic Dipole Currents

Propagation of electromagnetic signals through a non-conducting medium with very low density of neutral gas is considered with taking into account both electric and magnetic dipole currents. A new approach based on microscopic description of the medium and analytical solution of Maxwell equations in time domain has been used to solve the problem. The time delay between the signal precursor and its main lobe evaluated may be used for evaluation of either distance to a pulsar for the known medium parameters or those parameters for a given distance to the pulsar.Распространение электромагнитных сигналов через непроводящую среду нейтрального газа с очень низкой плотностью рассмотрено с учетом электрических и магнитных дипольных токов. Для решения этой задачи использован подход, основанный на микроскопическом описании среды и аналитическом решении уравнений Максвелла во временной области. Рассчитанная задержка между предшественником и главным лепестком сигнала может использоваться для оценки либо расстояния до пульсара при известных параметрах среды, либо параметров среды для известного расстояния до пульсара.Розповсюдження електромагнітних сигналів через непровідне середовище нейтрального газу з дуже низькою густиною розглянуте з урахуванням електричних та магнітних дипольних струмів. Для розв’язання цієї задачі використано підхід, що базується на мікроскопічному опису середовища та аналітичному розв’язку рівнянь Максвелла в часовій області. Розрахована затримка між попередником та головною пелюсткою сигналу може використовуватись для оцінки або відстані до пульсара при відомих параметрах середовища, або параметрів середовища для відомої відстані до пульсара

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Current oscillations in avalanche particle detectors with PNIPN-structure

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Theory of propagation of spectrum and correlations of radiation in optically dense gas in the case of the closed excitation contour

This work is devoted to generalization of the semi-classical theory of interaction of broadband laser radiation with the atomic gas at the room temperature in the cell in the case of the closed excitation contour. The atomic density matrix equations and spectrum and correlations transport equations have been derived for excitation by fluctuating field with Gaussian statistics. It is shown that the spatial oscillations of radiation intensity and atomic density matrix can be excited. It was found that such medium can serve as a filter of incoherent part of the radiation