Results 1 - 10 of 5166
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[en] The main objective of NEER grant was to generate highly accurate 2D and 3D time-dependent neutral particle intensity maps from 3D pulsed wire sources through integration of the analytical representation of a time-dependent point source
[en] A realistic characterization of the interaction of ions and neutral particles with device walls is important for any edge plasma calculation. Present reflection models vary in detail and computational efficiency. This paper presents a data set for the distribution of the reflection coefficient, RN, over reflected energy, polar, and azimuthal angles, as functions of incident polar angle and energy. These results have been computed using a vectorized version of the TRIM Monte Carlo code. The data are stored using an algorithm for reducing the data into three one-dimensional distributions, resulting in a realistic reflection model which can be used very efficiently in plasma edge calculations. (orig.)
[en] Classical transport of neutral particles in a binary, scattering, stochastic media is discussed. It is assumed that the cross-sections of the constituent materials and their volume fractions are known. The inner structure of the media is stochastic, but there exist a statistical knowledge about the lump sizes, shapes and arrangement. The transmission through the composite media depends on the specific heterogeneous realization of the media. The current research focuses on the averaged transmission through an ensemble of realizations, frm which an effective cross-section for the media can be derived. The problem of one dimensional transport in stochastic media has been studied extensively . In the one dimensional description of the problem, particles are transported along a line populated with alternating material segments of random lengths. The current work discusses transport in two-dimensional stochastic media. The phenomenon that is unique to the multi-dimensional description of the problem is obstacle bypassing. Obstacle bypassing tends to reduce the opacity of the media, thereby reducing its effective cross-section. The importance of this phenomenon depends on the manner in which the obstacles are arranged in the media. Results of transport simulations in multi-dimensional stochastic media are presented. Effective cross-sections derived from the simulations are compared against those obtained for the one-dimensional problem, and against those obtained from effective multi-dimensional models, which are partially based on a Markovian assumption
[en] An overview of the developments post-circa 1980's of the instrumentation and application of charge exchange neutral particle diagnostics on Magnetic Fusion Energy experiments is presented.
[en] The effect of the position where neutral particles enter the confined plasma region with closed magnetic surfaces on the radial profiles of the neutral flux and plasma density is numerically investigated. The case of elongated magnetic surfaces with X-point, in whose vicinity the metric coefficients are varying very fast with the radius of magnetic surfaces, is considered.
[en] First-neutral energy distribution function in inertial electrostatic confinement (IEC) plasmas is studied by solving the Boltzmann equation for fast neutral, which is produced by several kinds of charge-exchange reactions, for various presumed ion distribution functions. From the obtained fast-neutral distribution functions, the Doppler-shift spectrum (energy spectrum) of fast-neutral in IEC devices is evaluated. By comparing the spectra between the present calculation and previous experiment, the broadness of the ion distribution function in the energy space is estimated. (author)
[en] The principle of an 80 kW neutral-beam injector with the pulse of 4.2 A/28 kV and 25 ms width exptracted from an ion source was briefly described. The experiment results was reported in detail and compared with the results of theoretical value
[en] A new bipartition neutral transport model was developed for quick identification of the recycling properties of the wall-released hydrogenic neutral particles in the vicinity of the divertor target plate. Based on this model, the numerical calculation results are fairly consistent with the results obtained with the 'multi-generation method'. This model can not only be utilized to provide a source term from neutral transport calculations for the B2 edge plasma transport code, which has been used to simulate edge plasma transport of an HL-2A divertor configuration, but can also be specifically applied for fast classification of the divertor plasma as high recycling or low recycling. Our results also show that the transmissivity is lower in the high-recycling regime
[en] A new method for the solution of the coupled equations for the slowing-down of suprathermal ions and for the transport of neutral particles in plasmas is proposed; the combination of the multigroup methods recently developed for the solution of ion slowing down problems and of the neutral transport equation. The coupling between the suprathermal ion and neutral populations will be similar to the coupling between the neutron and photon populations in coupled neutron photon transport calculations. The coupled ions-neutral transport method proposed might be useful for accurate estimation of the performance, and for detailed design of different two-component plasma devices. It could be applied for the solution of a complete beam injection problem, starting with the calculation of the penetration of the neutral beam into the plasma, through beam ionization to the calculation of the slowing down of the ions taking into account charge exchange and reionization reactions. (B.G.)