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We explore a novel simulation route for Plasma Wakefield Acceleration (PWFA) by using the computational method known as the Lattice Boltzmann Method (LBM). LBM is based on a discretization of the continuum kinetic theory while assuring the convergence toward hydrodynamics for coarse-grained fields (i.e., density, velocity, etc.). LBM is an established numerical analysis tool in computational fluid dynamics, able to efficiently bridge between kinetic theory and hydrodynamics, but its application in the context of PWFA has never been investigated so far. This paper takes a step forward to fill this gap. Results of LBM simulations for PWFA are discussed and compared with those of a code (Architect) implementing a Cold Fluid (CF) model for the plasma. In the hydrodynamic framework, we discuss the importance of regularization effects related to diffusion properties intrinsic of the LBM, allowing to go beyond the CF approximations. Issues on computational efficiency are also addressed. [ABSTRACT FROM AUTHOR]

Air gap defects in solid insulation of power equipment can cause partial discharge. Temperature, as an important characterization of partial discharge, can be used as a criterion for the deterioration degree of air gap defects to some extent. In this paper, the temperature characterization of air gap discharge is studied. A plasma-kinetics-based dielectric barrier discharge model is constructed. The calculation method of air gap discharge heat source under power frequency voltage is presented. Moreover, the influence of voltage amplitude and gap thickness on temperature is studied. Obtained results indicate that under the power frequency voltage, Joule (Ohmic) heat contributes 90% to the heat source, and O4+ and O2+ and electron e are the main contributors to Joule (Ohmic) heat. O4+ is also the dominant ion in the mixed gas. As the discharge progressed, O4+ almost all clustered near the instantaneous cathode. The O2+ density generally depends on the electron density, but compared with the electron, the spatial distribution of O2+ density is slightly shifted to the instantaneous cathode. The discharge heat source is positively correlated with the air gap thickness and the voltage amplitude. With the increase in air gap thickness, the rising rate of heat sources will also increase. However, when the voltage is 10 kV, the heat source increases first and then decreases with the increase in the air gap thickness. The discharge does not occur when the air gap thickness reaches above 4 mm. This study provides theoretical support for identifying the deterioration degree of air gap defects from the view of temperature. [ABSTRACT FROM AUTHOR]

In this paper, the frequency and instability variations under the influence of temperature effect in a cylindrical smooth-bore magnetron are investigated. To derive the eigenvalue equation, the Fourier transform of electrostatic flute perturbations together with the local approximation method along radial direction for perturbed density is applied to equations of the macroscopic fluid model and Poisson equation. The obtained eigenvalue equation is solved numerically by shooting to a fitting point method. The analysis of numerical results shows the change in frequency of second three azimuthal modes for the case when the perpendicular temperature is higher than the parallel temperature ( T ∥ < T ⊥ ), which is greater than the case when temperatures along azimuthal and radial directions are equal ( T ∥ = T ⊥ ) or T ∥ > T ⊥ . As the temperature rising, the frequency and growth rate instability increase except for Tr > Tθ that the growth rate instability is reduced until Tθ = 100 00k and then is increased. The minimum frequency variation is 0.002 GHz for the mode of l = 1 at 2 T ∥ = T ⊥ . The maximum change in frequency, in contrast, is 10.651 GHz for the mode of l = 5 at 4 T ∥ = T ⊥ . According to the obtained results, the temperature controlling could be help to frequency adjustment in magnetrons. [ABSTRACT FROM AUTHOR]