Collisional ionization rates for lithium and beryllium-like ions

Collisional ionization rates for lithium and beryllium-like ions deduced from time history of spectral lines emitted by these ions in hot plasma

Experimental rate coefficients for collisional excitation of lithium-like ions

Collisional excitation rates for lithium-like ions derived from diagnosed plasma produced in theta pinch device and line intensities emitted by these ion

Flowing gas, non-nuclear experiments on the gas core reactor

Flow tests were conducted on models of the gas core (cavity) reactor. Variations in cavity wall and injection configurations were aimed at establishing flow patterns that give a maximum of the nuclear criticality eigenvalue. Correlation with the nuclear effect was made using multigroup diffusion theory normalized by previous benchmark critical experiments. Air was used to simulate the hydrogen propellant in the flow tests, and smoked air, argon, or freon to simulate the central nuclear fuel gas. All tests were run in the down-firing direction so that gravitational effects simulated the acceleration effect of a rocket. Results show that acceptable flow patterns with high volume fraction for the simulated nuclear fuel gas and high flow rate ratios of propellant to fuel can be obtained. Using a point injector for the fuel, good flow patterns are obtained by directing the outer gas at high velocity along the cavity wall, using louvered or oblique-angle-honeycomb injection schemes

Simplified models of electromagnetic and gravitational radiation damping

In previous work the authors analysed the global properties of an approximate model of radiation damping for charged particles. This work is put into context and related to the original motivation of understanding approximations used in the study of gravitational radiation damping. It is examined to what extent the results obtained previously depend on the particular model chosen. Comparisons are made with other models for gravitational and electromagnetic fields. The relation of the kinetic model for which theorems were proved to certain many-particle models with radiation damping is exhibited

Generalized CMB initial conditions with pre-equality magnetic fields

The most general initial conditions of CMB anisotropies, compatible with the presence of pre-equality magnetic fields, are derived. When the plasma is composed by photons, baryons, electrons, CDM particles and neutrinos, the initial data of the truncated Einstein-Boltzmann hierarchy contemplate one magnetized adiabatic mode and four (magnetized) non-adiabatic modes. After obtaining the analytical form of the various solutions, the Einstein-Boltzmann hierarchy is numerically integrated for the corresponding sets of initial data. The TT, TE and EE angular power spectra are illustrated and discussed for the magnetized generalization of the CDM-radiation mode, of the baryon-radiation mode and of the non-adiabatic mode of the neutrino sector. Mixtures of initial conditions are examined by requiring that the magnetized adiabatic mode dominates over the remaining non-adiabatic contributions. In the latter case, possible degeneracies between complementary sets of initial data might be avoided through the combined analysis of the TT, TE and EE angular power spectra at high multipoles (i.e. $\ell >1000$).Comment: 28 pages, 24 included figures in eps styl

Feasibility study of full-reactor gas core demonstration test

Separate studies of nuclear criticality, flow patterns, and thermodynamics for the gas core reactor concept have all given positive indications of its feasibility. However, before serious design for a full scale gas core application can be made, feasibility must be shown for operation with full interaction of the nuclear, thermal, and hydraulic effects. A minimum sized, and hence minimum expense, test arrangement is considered for a full gas core configuration. It is shown that the hydrogen coolant scattering effects dominate the nuclear considerations at elevated temperatures. A cavity diameter of somewhat larger than 4 ft (122 cm) will be needed if temperatures high enough to vaporize uranium are to be achieved

Birefringence, CMB polarization and magnetized B-mode

Even in the absence of a sizable tensor contribution, a B-mode polarization can be generated because of the competition between a pseudo-scalar background and pre-decoupling magnetic fields. By investigating the dispersion relations of a magnetoactive plasma supplemented by a pseudo-scalar interaction, the total B-mode polarization is shown to depend not only upon the plasma and Larmor frequencies but also on the pseudo-scalar rotation rate. If the (angular) frequency channels of a given experiment are larger than the pseudo-scalar rotation rate, the only possible source of (frequency dependent) B-mode autocorrelations must be attributed to Faraday rotation. In the opposite case the pseudo-scalar contribution dominates and the total rate becomes, in practice, frequency-independent. The B-mode cross-correlations can be used, under certain conditions, to break the degeneracy by disentangling the two birefringent contributions.Comment: 8 pages, 2 figure