Vacuum Chamber gets Titanium Nitride Coating, New Window as Tests NearDecember 7, 2015
As preparations for the next set of experiments accelerate, LPPFusion has received the newly coated vacuum chamber parts back from suppliers in Ohio and NJ. The parts have been coated with titanium nitride in order to minimize the oxygen in the chamber. On the one hand, the coating will act as a sponge soaking up any hot oxygen produced during the shots of the FF-1 experimental device. On the other hand, the titanium will tightly grip the oxygen, not allowing it to be torn away during a following shot.
The point of greatly reducing the oxygen is to prevent the formation of tungsten oxide on the tungsten electrodes. Since the metal tungsten is extremely heat resistant, while tungsten oxide is not, reducing tungsten oxide also reduces the tungsten impurities released into the plasma. Reducing the impurities is the key to increasing the density of the plasma and thus the fusion energy produced.
The vacuum chamber assembly will begin within days. Other upgrades to the chamber include a large quartz window, replacing a copper one, for x-ray instruments. The quartz window is far more resistant to giving up oxygen than the copper one. It will also afford the research team a good view of the electrodes and insulator during the experiment as it is transparent. Once the chamber is assembled and pumped down to a vacuum, it will be wrapped in a heating and insulating blanket, currently being fabricated, which will bake it for five days at 150° C. The baking will eliminate the vast majority of the oxygen that inevitably clings to metal parts. That will prepare the device for the next experimental series before the end of December.
Figure 1. FF-1’s drift tube looks good as gold with its titanium nitride coating. The surface shown on left is the top of the drift tube and the bottom of the main vacuum chamber. The outer surface (right) was also coated during the plasma-based deposition process, although since it is not exposed to the plasma, the coating serves no purpose (except possibly decorative!). The tube had to be cut to this size to fit in the coating chamber. It will be welded to an uncoated lower section. Coating is not needed on the lower section as it will not be exposed to high enough temperature to tear off oxygen.