Parkhomov starts with a 10mm OD alumina tube with a 5mm ID bore (so the wall of the tube is 2.5mm thick). He plugs both ends with an alumina rod and "cement" with the fuel inside. He hasn't said what "cement" he uses to hermetically seal the plugs in the tubing, but he does say that it is a hard 3-day process. After the hermetic plugged tube assembly is made he winds this tube directly with a nichrome wire coil and paints it all over with a thick alumina cement. MFMP has asked Parkhomov what he used for cement and what his hermetic sealing process was and he has not yet responded.
In the mean time MFMP is discussing using a high temperature glass frit seal for the plug. One end is already molded and fired closed - the tube was purchased that way. So the fuel will be added, then an alumina wool plug near the seal end, then the alumina plug painted with a glass frit paste having a resulting thermal expansion matched to alumina. Then the fuel end will be cooled while the seal end is heated with a torch to melt the seal glass and form a hermetic seal. This is the MFMP "reaction tube", about 0.25" OD. The dogbone heater coil is wrapped around another alumina tube into which the reaction tube can be inserted (slightly larger than 0.25" ID). This allows the reaction tube to be replaced without having to wind a new heater coil and overmold it for every experiment. In MFMP testing, the previously fueled and sealed reactor tube is inserted into a dogbone heater tube that has the coil wrapped and enclosed in molded alumina cement. Power is applied to the dogbone heater coil which heats the reactor tube that was slipped inside. Bob On Thu, Jan 1, 2015 at 12:24 PM, Bob Cook <frobertc...@hotmail.com> wrote: > Bob-- > > How does Parkhomov get a uniform thickness of alumina cement, whatever > that is, between the 2.5mm alumina tube (reactor tube in previous > correspondence) and the alumina dogbone with the electrical heater wires? > It may be that I do not understand the physical arrangement of the various > alumina components of the Parkhomov experiment. > > Bob >
