Thursday

Sputter coater

The sputter coater has 2 valves that control the exhaust (for when you want the chamber to return to atmospheric pressure) and the other for filling the chamber with the gas of your choice. In order to determine if the release valve is the culprit for our leak, I did the following things.

  • Removed the release valve and re-Teflon taped the filter and hose connected to it.
  • Completely bypassed the release valve and rigged together a manual release valve.

Neither of these things worked. Rather than try to fuss with the valves, I am going to remove all connections to the chamber and try to find a way to test pressure inline with the vacuum pump. Perhaps the actual chamber is the problem.

  • Plug all connections to the chamber and test.

If the chamber isn’t the problem, then it may be the pressure gauge. That, I can’t fix and will be an absolute bear if we need to replace it since the machine is out of production.

Roughness

Continuing with my other interests in roughness, I obtained the original Hamaker publication which talks about the aptly “Hamaker coefficient” that I have been reading about. I plan to rederive the coefficient for two spherical bodies as it should be interesting.

I have been able to read Hamaker’s original article

Hamaker HC (1937) The London-van der Waals attraction between spherical particles. Physica 4:1058–1072. http://dx.doi.org/10.1016/S0031-8914(37)80203-7.

and I have worked through his calculations. I am getting a sign error for some reason and will have to investigate that later. In the very least, it feels good to do some math and flex my integrating muscles. I’ll post my calculations in a later post.

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