While FF-1 can’t fire until it gets the new tungsten cathode, the lab has not been sitting idle. The LPPF team has undertaken significant upgrades to the device, and started work on further ones. Other than a complete disassembly, cleaning and re-assembly of the vacuum chamber and drift tube to eliminate all sources of impurities, the team has improved assembly techniques to achieve greater symmetry in the device and greater protection for the new cathode itself.
One key improvement is in the process of centering the cathode, the outer electrode, on the anode, the inner electrode. Since there is a tight fit between the two electrodes and the insulator sandwiched between them, any slight asymmetry can affect the amount of plasma trapped in the small space between the parts, and thus potentially the speed of the rundown and the symmetry of the pinch. In the past, centering was done by shimming the part with plastic shims. Now, however, precision micrometer adjustment devices will be mounted on four sides of the steel plate that is attached to the monolithic tungsten cathode (see drawing). The micrometer will allow centering of the cathode on the anode to a precision of 25 microns or less and make the process far faster than the shimming. The design work was performed by Consulting Engineers Jonathan Klabacha and Tony Ellis and our new volunteer engineer, Marc-Antoine Legault.
We are also preparing for a further stage of our experiment, when we switch from using deuterium as a fuel to our final aneutronic fuel, hydrogen-boron or pB11. We have checked our 250-gm supply of decaborane—the compound of hydrogen and boron we intend to use and Chief Research Officer Dr. Hamid R. Yousefi has selected the safety equipment we need, such as glove boxes to handle the material, whose vapor is somewhat noxious. We are in the process of designing and purchasing the equipment needed to heat the device to approximately 120 C, needed to create the vapor pressure to fill the vacuum chamber. While it is still months before we are ready to run with decaborane, we will be ready to make the transition with as few delays as possible.
In addition, we are undertaking a major upgrade of our computers and data processing, which we will report on next month.