Particle-in-Cell Modeling of Laser Thomson Scattering in Low-Density Plasmas at Elevated Laser Intensities
Incoherent Thomson scattering is a non-intrusive technique commonly used for measuring local plasma density. Within low-density, low-temperature plasma's and for sufficient laser intensity, the laser may perturb the local electron density via the ponderomotive force, causing the diagnostic to become intrusive and leading to erroneous results. A theoretical model for this effect is validated numerically via kinetic simulations of a quasi-neutral plasma using the Particle-in-Cell technique.
Particle-in-cell simulation feasibility test for analysis of non-collective Thomson scattering as a diagnostic method in ITER
Abstract The feasibility of the particle-in-cell (PIC) method is assessed to simulate the non-collective phenomena like non-collective Thomson scattering (TS). The non-collective TS in the laser-plasma interaction, which is related to the single-particle behavior, is simulated through a 2D relativistic PIC code (XOOPIC). For this simulation, a non-collective TS is emitted from a 50-50 DT plasma with electron density and temperature of n e = 3.00 × 1 0 13 cm − 3 and T e = 1000 eV , typical for the edge plasma at ITER measured by ETS system, respectively. The wavelength, intensity, and FWHM of the laser applied in the ETS system are λ i , 0 = 1.064 × 10 − 4 cm , I i = 2.24 × 10 17 erg / s ⋅ cm 2 , and 12.00 ns , respectively. The electron density and temperature predicted by the PIC simulation, obtained from the TS scattered wave, are n e , TS = 2.91 × 10 13 cm − 3 and T e , TS = 1089 eV , respectively, which are in accordance with the input values of the simulated plasma. The obtained results indicate that the ambiguities rising due to the contradiction between the PIC statistical collective mechanism caused by the super-particle concept and the non-collective nature of TS are resolved. The ability and validity to use PIC method to study the non-collective regimes are verified.
Extranasal type of nasal glioma
Summary A case of a rare congenital tumor; a nasal glioma of the extranasal type has been presented which seems sufficiently unusual to be worthy of reporting. The various theories as to the origin and nature of these lesions have been discussed in the paper by Hill6 and others, 1, 2, 5 but it is the belief of the authors that most or probably all of these lesions represent a congenital malformation.