After a great night's sleep at 9,500 ft / ±3 km altitude, the jetlag (and the fact that I forgot to close the blinds) helped out fantastically to start the day bright and early at 5.45 AM. There is only capacity for a few of the MMAMA people to stay up the mountain and since I'm serving in the science team meetings that wil run in the evenings, I get to stay up at the Hale Pohaku lodges again, instead of having to drive up and down from sea level for an hour and a bit. This does have its perks - I get a bit better adjusted to the altitude - and it's consequences - I get to get up at 6.00 and start working around 7.00 AM and am still running samples at 21.00 (9.00 PM).
Today was another day to troubleshoot the instrument and get stuff working and we clearly needed it. Both VAPoR and MeSH seem to have had some trouble with the journey here.
* good news - the leak seems to be gone - we opened up and resealed the oven and now the pressure goes nicely down to somewhere in the 10-7 mbar range. low enough to operate the mass spectrometer
* bad news - the serial port of the laptop has decided to give up
* relatively good news - Magnus had a serial-to-usb converter that did work
* more bad news - the LabView software we use seems to be hard coded to the old serial port and does not want the recognize the new port.
* short intermezzo - we built a LabView program to run all the different parts of VAPoR and collect all data in one big file, so mass spec and temperature and pressure and oven power data.
* the solution - we forget about LabView for now and just as in the early days, we control the temperature straight from the controller and the mass spec using it's own software again. back to taking notes about the temperature and pressure every 5 mins in the labbook and then manually transferring them to the computer. the mass spec data will be analyzed using an excel work around.
Technically, we should be up and running tomorrow at the first day of the official tests. I'm running a blank now to save us some time tomorrow, but we should be all good.
* some strange demon has decided to randomly spike up the current of the motor, still not figured out why, but it's not posing too much of a problem
* a few of the sensors that help putting the instrument back in the "home" position decided to call it quits, but also for that we found a work around.
Good end of the day, though, with two nicely ground blanks, one of which to be measured tomorrow morning.
Just in short again how VAPoR and MeSH work:
A sample is delivered to MeSH, which crushes and sieves the sample to 150 micron. The crushed sample is then transfered to a sample holder and placed inside the VAPoR oven in the carousel. The carousel is then rotated under the mass spectrometer, a vacuum tight seal is created and the system is pumped to vacuum. The sample is heated to 1000 °C at a rate of 20 °C/min and the gases that evolve are analyzed by the mass spectrometer.
Here a neat little video on how MeSH operates:
So all in all everything seems to be good to go for the real test! More about that in the next blog.