Reply To: General thought on old coal mines.

[jamesr]

The bremsstrahlung is minimized by the specific level of the mag field, IIRC, not by keeping the thermal energy high. As far as the field lines of the plasma containing the heavier nuclei, I assume that they are all ionized, and hence tightly contained.

The quantum effect when the electron larmor radius due to a strong magnetic field is of the order of its de Broglie wavelength is a small (but key) factor, in that it may reduce bremsstrahlung from boron by a factor of 5 or so. Even with this effect the plasma would radiate its energy away and cool to well below the temperature needed for fusion in picoseconds rather than the nanoseconds needed to burn enough fuel to get nett energy gain. It is the recycling of energy from the helium to keep the hydrogen and boron hot enough for long enough that will make it viable.

At the magnetic field strengths involved, yes, the ions are well confined, and are bound to follow the field lines (gyrating around them). But no magnetic confinement is perfect, as collisions cause diffusion and transport of ions away from the dense core. Once an ion has scattered out to the last closed field line, or separatrix, of the plasmoid it will escape.

The question is – what is the probability for tritons or alphas that are created sufficiently close to the edge to have a chance of escaping before they have given up all their energy