High-power radiating plasma

The physical principles underlying the use of radiating plasmas for the optical pumping of lasers are described. Particular consideration is given to the properties of radiating plasmas; radiation selectivity; the dynamics, equilibrium, and stability of radiating plasmas; the radiative Reynolds number; and experimental results on radiating discharges

Interaction of ultrarelativistic electron and proton bunches with dense plasmas

Here we discuss the possibility of employment of ultrarelativistic electron and proton bunches for generation of high plasma wakefields in dense plasmas due to the Cherenkov resonance plasma-bunch interaction. We estimate the maximum amplitude of such a wake and minimum system length at which the maximum amplitude can be generated at the given bunch parameters.Comment: 8 page

Experimental Study of the Effect of External Signal on Microwave Oscillations in a Nonrelativistic Electron Beam with Virtual Cathode

The effect of an external harmonic signal on the characteristics of microwave generation in a nonrelativistic electron beam with virtual cathode (VC) formed in a static retarding electric field (low-voltage vircator system) has been experimentally studied. A significant increase in the vircator generation power is observed when the frequency of the external signal is close to the frequency of VC oscillations. At large detunings, a broadband chaotic generation is observed.Comment: 3 pages, 2 figure

On the Static Dielectric Permittivity for Coulomb System in the Long Wavelength Limit

On the basis of the exact relations the general formula for the static dielectric permittivity for Coulomb system is found in the region of small wave vectors. The obtained formula describes the dielectric function of the Coulomb system in both limits: in the "metallic" state and in the "dielectric" one. On this basis the determinations of the "apparent" dielectric and the "apparent" radius of screening are introduced. In the random phase approximation (RPA) the exact relations for the function dielectric function of the electron gas in the long-wavelength region of the wave vectors are found for an arbitrary degeneration of the particles.Comment: 5 pages, no figure

Vlasov-Maxwell, self-consistent electromagnetic wave emission simulations in the solar corona

1.5D Vlasov-Maxwell simulations are employed to model electromagnetic emission generation in a fully self-consistent plasma kinetic model for the first time in the solar physics context. The simulations mimic the plasma emission mechanism and Larmor drift instability in a plasma thread that connects the Sun to Earth with the spatial scales compressed appropriately. The effects of spatial density gradients on the generation of electromagnetic radiation are investigated. It is shown that 1.5D inhomogeneous plasma with a uniform background magnetic field directed transverse to the density gradient is aperiodically unstable to Larmor-drift instability. The latter results in a novel effect of generation of electromagnetic emission at plasma frequency. When density gradient is removed (i.e. when plasma becomes stable to Larmor-drift instability) and a $low$ density, super-thermal, hot beam is injected along the domain, in the direction perpendicular to the magnetic field, plasma emission mechanism generates non-escaping Langmuir type oscillations which in turn generate escaping electromagnetic radiation. It is found that in the spatial location where the beam is injected, the standing waves, oscillating at the plasma frequency, are excited. These can be used to interpret the horizontal strips observed in some dynamical spectra. Quasilinear theory predictions: (i) the electron free streaming and (ii) the beam long relaxation time, in accord with the analytic expressions, are corroborated via direct, fully-kinetic simulation. Finally, the interplay of Larmor-drift instability and plasma emission mechanism is studied by considering $dense$ electron beam in the Larmor-drift unstable (inhomogeneous) plasma. http://www.maths.qmul.ac.uk/~tsiklauri/movie1.mpg * http://www.maths.qmul.ac.uk/~tsiklauri/movie2.mpg * http://www.maths.qmul.ac.uk/~tsiklauri/movie3.mpgComment: Solar Physics (in press, the final, accepted version

Searches for neutrinoless double beta decay

Neutrinoless double beta decay is a lepton number violating process whose observation would also establish that neutrinos are their own anti-particles. There are many experimental efforts with a variety of techniques. Some (EXO, Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has reported the first measurement of the half life for the double beta decay with two neutrinos of $^{136}$Xe. The sensitivities of the different proposals are reviewed.Comment: 8 pages, prepared for TAUP 201