Smooth Turkey Chamber Baking

The endless strive to deliver a perfect turkey by the Thanksgiving is continued. Today, I have verified,

1. A flawless performance of the "Peteometer."
2. Perfect temperature setting for turkey cooking.
3. A new lower bound temperature of coolant without dangerous overheating of the water pump.

Although on my way to these new discoveries, I have encountered an unexpected activation of the Peteometer relay due to electrical noise upon interface with a data-logging computer. This shut down is not hazardous at all but it delayed the initial pump down rate of our turkey chamber. 

The rubber o-rings supporting the high vacuum environment inside the chamber can hold up to 270F. If the baking temperature exceeds this threshold, o-rings will melt and catastrophic vacuum leak will form which will surely to cause extremely hot supersonic diffusion pump oil to backdraft all the way through the mechanical pump messing up our entire pumping systems. For this reason, the set temperature for baking is fixed to 80 degrees Celsius well below the threshold. When I left the system yesterday night, an internal pressure reading was steady at 1.9-2.2 e-5 torr. Today, the pressure seemed to have dropped to 9.0 +-0.5 e-6 torr suggesting the baking is indeed working. 

This little pressure display is my only way to 
know the pressure of the chamber

The Peteometer display showing outlet coolant temperature. 
The inlet coolant temperature was set at 9.

The mass spectrometer we use to identify the types of limiting gases preventing the internal pressure from getting pumped down to our desired level of operation uses an MS-DOS program. Since Microsoft stopped developing this several years ago, for this very purpose of using mass spectrometer, we are forced to use an ancient computer running Windows 95 which was developed around the time I was a happy kindergartener? Of course, I don't even get to use the "Windows," only MS-DOS. 


I have initially run mass spectroscopy inside the turkey chamber before the baking so that I have something to compare to later when I run another measurement of the chamber. The following graph shows a contrast between before/after the baking process.

Click on the figure for details

A comparison between the initial measurement (blue) and the most current measurement (green) shows that water vapor pressure (atomic mass 18) indeed dropped due to the baking process. The rest of gases changed only a little, but they are also expected to drop as the baking continues. Nitrogen (atomic mass 28) is another gas significantly affecting the overall pressure inside the chamber. Although this hasn't changed that much based on the three measurements done over the course of a day, the nitrogen vapor pressure is expected to go down pretty soon. Maybe the temperature isn't just enough for the nitrogen, although it's good for water? You know what, I may as well just go down the basement and increase the baking temperature a bit more.... Yeah.

(Update...)
So I did raised the temperature to 95 centigrade. Now, I should go to the Music building and play guitar as a reward. Nothing is better than a good old tune o' guitar after a hard work.


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