Russian Group Achieves pB11 Fusion With Very Small Yield
A Russian team of researchers reported observing pB11 fusion using a laser. The yield was only about 1,000 reactions, about 7 billion-fold short of breakeven, but the experiment did show that pb11 fuel will burn more or less as expected.
The team exposed a solid target of borated plastic to a 1.5 picoseconds, 10-joule laser pulse concentrated in an area 7 microns in radius. A very thin, 0.024 micron layer was heated to an electron temperature of about 100keV and an ion temperature of 30 kegs. The confinement-time-density product was 1.1x1011, much smaller than the nearly 1014 we achieved with an ion temperature of 55 keV. However we did not use pB11 but instead used deuterium fuel.
The laser approach can not be easily scaled up to breakeven. Higher laser intensities will increase yield, relative to input energy, by only about a factor of 300 at solid densities. For breakeven, compression to densities more than 5,000 times solid density would be required. Decades of efforts on laser fusion show that such high compression is just about impossible to achieve.