OK, lets assume that your plasma 'leakage' is low (zero) and other loses are minimized (again, zero) so your containment energy cost is near zero and few ions lose energy by Bremsstrahlug (again, zero - all impossible but use this as the best case since it is); now, calculate how many ions achieve fusion via tunneling per sec in your 10 -100 micron gas; then calculate the energy so obtained from these fusion events (hint -

**many orders of magnitude lower**than the 250 watts that a cubic meter of the Sun's ultra dense and super hot core releases every second) - in other words, if you were 100% perfect you're gonna get maybe 10^-3 watts per second for a cubic meter of plasma! Think this out - that assumes essentially zero losses and near 100% conversion of all possible tunneling captures per sec resulting in less energy production than a flashlight bulb yields in radiated energy/sec.

I could point out your claim that you get sufficiently low leakage out the ends that your net energy loss is less than fusion produces because you say so is not proof - as to why it will leak terribly and not trap your ions as you think can be shown by reading some of the vast scientific literature on mirror machines in fusion and their issues.

By the way, that is why tokamaks and stellarators were built - the ends are connected allowing the trapped ions to circulate as long as the plasma is stable (why that is not true for times past a few seconds isn't the point. Energy produced per sec tells us all we need to know.) In these devices, fusion via tunneling is essentially nil. So, why would yours produce more energy?