The next step beyond the new experiments with the existing tungsten electrodes is the installation of the beryllium anode, expected to arrive in September. This will be the first time that a beryllium electrode has been used in any plasma focus device, an idea covered by LPPFusion’s patents. While most work is still concentrated on the all-tungsten experiments, the LPP Fusion research team is also getting ready for beryllium. As a light metal, with only 4 electric charges per atom, beryllium will produce hundreds of times less impurity impact on the plasma than tungsten does, for equal energy inputs.
Beryllium metal by itself is harmless, but unfortunately beryllium dust is highly toxic to many people. So the first task was consulting with beryllium experts to find out the safest methods for handling even the tiny amounts of beryllium dust that may be produced by firing FF-1 with a beryllium anode. The good news is that beryllium dust will only be produced within the sealed vacuum chamber, where the dust can be safely flushed out with nitrogen. The dust will be trapped in HEPA filters, which will eventually be safely disposed of with local hazardous waste firms. To be doubly sure, we will probably install a sampling chamber so that a sample of the gas in the chamber can be checked at a local lab for dust before the chamber is opened.
In addition, the team is in the final stages of designing a small upper vacuum chamber that will be used to measure the electron beam produced by FF-1. The beryllium anode will have a central hole drilled all the way through to allow the electron beam to escape. In the upper chamber, the beam will be diverted by a magnetic field, allowing the distribution of electron energies to be measured. Care is being devoted to making sure that the electrodes themselves are adequately shielded against the magnetic field, which can introduce asymmetries in the formation of current sheath within the device.