Electrical conductivity of metals at high temperature

About 20 years ago, I developed a computer code for Los Alamos National Laboratory to model imploding liners: cylindrical shells driven inward with intense magnetic pressure to produce a strong on-axis shock. The model required continuous curves of electrical conductivity for metals over a broad temperature range — room temperature to ~100 million °K. The data may [...]

Thermal effects in space-charge-limited flow

This article includes universal curves of the effects of source temperature on the space-charge-limited extraction of charged particles to form beams. The main result is that the current density may exceed the Child limit (discussed in a previous article) when the thermal energy of source particles (kT) is a significant fraction of the extraction energy (qV0). [...]

Creating a Maxwell-Boltzmann particle distribution

A common task in computer calculations in collective physics is the generation of input particles with a desired probability distribution in energy, angle or position. This article discusses some easy methods to accomplish the task using a software module to manipulate tabular functions. As an example, we’ll consider creating a Maxwell-Boltzmann distribution in kinetic energy U.

As [...]

Space-charge-limited flow from a thermionic source

In my role of writing and maintaining the Trak and OmniTrak codes, I often think about electron-beam extractors. The critical issues are limits on current density and beam coherence. Both may be affected by the temperature of thermionic cathodes. The topic was studied theoretically almost a century ago by Langmuir [ I. Langmuir, Phys. Rev. 21, [...]

Rules for coordinate units

Distance units are a potential source of confusion in scientific work. It is often convenient to work in convenient units like centimeters or microns, but we must ensure that the physical calculations are performed in consistent SI units. Rules for using units in our software are discussed in several sections of the instruction manuals. I thought [...]