The Effect of Specific Heat Ratio on Neutron Yield

It is known that the radius ratio of a plasma
pinch depends on the specific heat ratio γ of the pinch plasma,
where radius pinch ratio is defined as: radius of plasma pinch
column/radius of anode. The lower the specific heat ratio the
lower would be the pinch radius ratio with corresponding
increased compression and pinch density. The deuterium plasma
focus pinch is invariably fully ionized and has a specific heat ratio
of practically the highest possible value of 5/3. If the deuterium
plasma focus could have its specific heat ratio reduced below 5/3
we might expect its radius ratio to be correspondingly reduced,
increasing the pinch density, thus improving the D–D fusion
neutron yield. To demonstrate this effect we run the Lee model
code in deuterium but hypothetically fix the specific heat ratio,
reducing it at each run. The results show that indeed the radius
ratio is reduced, increasing the compression, and the neutron
yield is substantially increased. The effect is used to explain the
observed neutron yield enhancement when a deuterium plasma
focus doped with a small amount of krypton.