Model Computer Code Research Articles

Pulse shape and laser-energy extraction from e-beam-pumped KrF

In this paper, detailed comparisons are made between the numerical predictions of a comprehensive KrF kinetics/laser-model computer code and the experimental results from an e-beam-pumped KrF laser. The code and the experimental laser device are described. The inputs to the code are the measured temporally varying e-beam energy and current density, the laser mixture, the optical-cavity output coupling, and the optical gain length. Comparisons include laser output power, laser output pulse shape, and KrF* fluorescence from the laser-cavity sidelight under lasing and nonlasing conditions. Using our numerical model, we have generated a scaling map for the KrF* laser.

Charge Exchange Losses during Cyclotron Acceleration: Experiment and Theory

Quantitative estimates of charge exchange (CE) losses during acceleration are very important in the design and operation of heavy ion cyclotrons. Such estimates have been made using a vacuum model computer code which was developed to establish vacuum requirements for the MSU superconducting heavy ion cyclotron. This code uses pressure and cross-section data to calculate the radial loss of beam due to charge exchange. Since CE cross sections and radial pressure profiles are not always well known, certain specific measurements have been made using the LBL 88-Inch Cyclotron to provide experimental data needed to test the code. These include measurements of pressure versus radius under vacuum conditions closely approximating those existing during acceleration of 14N4+ and 40Ar8+ beams. Beam intensity versus radius data demonstrating transmission losses for three beams are presented. Comparisons with theoretical predictions are given.

Rain scavenging of SO2and sulfate from power plant plumes

A model has been developed for prediction of the reversible washout of SO2 emitted from power plant plumes and other sources. Predictions of this computer code model compare favorably with washout measurements made during a number of controlled source experiments and four power plant experiments. An application of the model to previous experimental conditions of high background rain acidity shows that ‘negative washout’ can occur as a result of desorption of SO2 from the rain below the SO2 plume. Scavenging rates (cross-plume integrated fluxes) measured during the power plant study show that the rate of deposition of sulfate was 1–5 times greater than that of SO2 at distances from 0.4 to 11 km from the stack. The experimental results were applied to two very simple SO2 oxidation models: one involving liquid phase (raindrop) oxidation and one considering ‘in-plume’ oxidation. Either mechanism appears to be compatible with the observations if the SO2-sulfate reaction half time in each case is of the order of 0.07 h. This result follows from a number of assumptions, including a reasonable washout coefficient for sulfate in the in-plume case and equilibrium SO2 washout in the liquid phase case.

Cooling by Discrete and Porous Injection into a Turbulent, Supersonic Boundary Layer

A summary is provided of an experimental investigation which was carried out to determine the cooling effectiveness of an injection of water through slotted and porous surfaces into a turbulent, supersonic boundary layer. Correlations, based on the experimental data and the supporting analysis, were incorporated into a computer-code model. The model is used to compute discrete injection coolant flow rate requirements for arbitrary slot sizes and heating environments.