Electron temperatures and thermal conduction in high-energy θ pinches

The common occurrence of electron temperatures of a few hundred electron volts in $\theta$ ‐pinch experiments is shown by simple analytic arguments to be rather tightly determined by a balance between energy gained from collisions with the much higher‐temperature ions and thermal conduction to material walls. It is also shown that electron thermal conduction should not cause a greater loss of energy from straight $\theta$ pinches of any length than ion end loss unless rather large magnetic mirror ratios can be obtained. This applies in particular to straight $\theta$ ‐pinch fusion feasibility experiments and fusion reactors. Also several suggestions are presented for reducing end losses and heating plasma columns.