BLP Gas-Phase Replication Effort - Run 6….16JAN98 ………………..(best viewed with 1024 pixel display width)
Legend
Total Input Power (electrical)
Output Power (heat)
Chamber Wall Temperature (C)
Gas Temperature (C)
Gas Pressure (torr)
Filament Resistance (ohms)
Room Temperature (C)
Inlet water Temperature (C)
For this run we removed the KNO3 from the chamber and replaced it with 0.08 grams of 1%Pd-on-activated-carbon, a catalyst material similar to that used in some of the BLP experiments. During the bakeout period, we also evacuated and baked out the hydrogen purifier in an effort to eliminate water vapor from the system. We also adopted a modified protocol designed to preserve the tungsten filament as much as possible.
The run starts with 20 minutes of zero input power where only the vacuum pumps are running. Then we applied 30 watts to the cartridge heater but left the filament off. About 2.5 hours into the run, we applied 15 watts to the filament and reduced the cartridge heater power to 15 watts. Filament temperature rose promptly to about 2100° C (calculated from the observed resistance change). We maintained these conditions until about 3.5 hours into the run and then admitted 2 torr of H2 gas to the chamber and closed it off. Note the sudden decrease in filament temperature (Tfil) when the highly conductive H2 gas was admitted. Immediately upon admitting the H2 gas into the chamber the Tfil trace began a slow steady ramp upwards…indicating erosion of the filament. Just after hour 4.0, we increased the filament power to 25 watts and lowered the cartridge heater power to 5 watts (marked by a sudden increase in the Tfil trace). As might be expected, the erosion rate of the filament increased and the Tfil trace headed upwards at an ever increasing slope. This time we did a better job of keeping the total input power constant during the filament's remaining life. The frequent adjustments necessitated by the ever-changing filament resistance caused the visible jitter in the Pin trace. At about 5.0 hours into the run, the Tgas reading began to act up again…just like it did in Run 5!!!! The coincidence was too much…there had to be some correlation with what was happening in the chamber.
The filament burned out at about 6.2 hours into the run and the Tgas signal recovered promptly (the trace doesn't recover instantly because the data is smoothed with a digital filter). Hypothesis: During the final minutes of the filament's life, portions of it become so hot that electron emission creates a significant current that flows from the 60Hz AC-driven filament through the gas to the un-grounded thermocouple, disturbing the sensitive amplifier that couples it to the data acquisition system.
Conclusions:
We still have the filament erosion problem. It is probably not due to the present of KNO3 in the chamber (although there could be traces of KNO3 remaining in the chamber).
This run didn't show an excess heat effect. During the 1.7 hours that the filament was operating with H2 gas in the chamber the Pout trace approached the Pin trace beautifully. Of course we didn't have any K in the chamber so this result is not too meaningful unless you expect the 1%Pd-on-activated-carbon catalyst to make hydrinos, too.
The floor is open for comments and suggestions for Run 7.
P.S. I have to amend my gripe about the Omega TAC80B-K Temperature-to-Analog Converter. It is apparently not at fault in the Tgas signal excursions but it is still a shoddy piece of work. The construction is cheap and flimsy. The AC power connector keeps falling out of its socket. The switches feel like they'll last about 10 more cycles….