Reply To: Barack Obama on Energy

[asymmetric_implosion]

Why is everyone hung up on Be and C-based materials? Be is a mess of a material. It is toxic and can produce neutrons when hit by hard x-rays. The cost is a real problem too. Non diamond, C-based materials are susceptible to hydrogen etching and they generally have a poor electrical and thermal conductivity compared to metals. Based upon published studies about 20% of the bank power ends up on the anode when you have a highly electrically conductive metal and must be removed as heat. For a high repetition rate application like power generation, a modest resistivity material like graphite will only increase the heat load. As the electrodes get hot they tend to emit impurities or form other materials such as BC4 (insulator) in the presence of boron.

Studies were conducted nearly twenty years ago on electrode materials for plasma focus devices and the “best” materials were operated at up to 80 Hz (80 times a second) for 5 million shots. The winner was Molybdenum. It is a higher Z material which increases the x-ray dose a bit but the x-ray can generally be shielded with less than 0.5″ of lead or tungsten. The lead or tungsten shield is far less costly than a Be electrode.

It’s great folks are thinking outside the box from the typical copper electrode, but this was thoroughly studied in past experiments considering many of the key factors for fusion yield. Why reinvent the wheel when the wheel is well studied and it works?