[RASMB] Elevated temperature operation with a turbomoledcular pump.

[Dmitry Veprintsev]

Dear Walter,
I would be interested in it as misting up is a real problem.
How much did it cost to replace?
regards, Dmitry

Walter Stafford wrote:

> Dear RASMB-ers
>
>     I have been testing a turbomolecular pump as a replacement for the 
> standard diffusion pump on the XL-I. I am writing to report the 
> results of that experiment.
>
> On my machine, with the standard diffusion pump installed, I have not 
> been able to run above about 23 degrees without having serious fogging 
> of the interference condensing lens after about 15 minutes, making it 
> impossible to take data.
>
> About a month ago, with the help of the Beckman Serviceman and folks 
> from the Axiden Division of Alcatel Vacuum Technology 
> {http://www.adixen-usa.com/}, we installed an ATP80 TMP in place of 
> the diffusion pump. Other than a flange that had to be machined to 
> mate the TMP to the diffusion pump flange, it was a direct 
> replacement. The original rough pump was used to back up the TMP.  
> see: 
> {http://www.adixen.com/all/dyn/products/products.php?id_prod=20&lg=us}
>
> So far the results have been quite remarkable. After the first test of 
> running for 4 days at 40 degrees, the optics were clean. The chamber 
> was actually cleaner after the run than before. The TMP seemed to have 
> removed all the residual oil that we were unable to remove after 
> replacing the diffusion pump. It pumps down to 3-5 micons in less than 
> 5 minutes and ultimately to about 1-2 microns. The fringe patterns 
> seem to be more stable (not sure exactly why, but I was informed that 
> the regular diffusion pump heater normally cycles on and off; the 
> flexing associated with that may explain it).
>
> We use it routinely now for all runs and couldn't be happier with it.
>
> Several labs have expressed an interest in installing one on their 
> machines.
>
> However, Beckman will not support the pump or provide one as standard 
> equipment unless there is sufficient interest. A proper, Murphy-proof 
> installation would require a firmware change and field service support 
> to allow it to be included under the service contract and warranty.
>
> I would like to take a survey of those who might be interested, so 
> that we can convey that expression of interest to Beckman.
>
> If you have an interest and think that running at higher than 20 
> degrees or higher precision might be useful to you, please respond to 
> this email by replying to the RASMB. I'll collect the responses and 
> comments and forward them to the folks at Beckman.
>
> It has opened new vistas for our research.
>
> Thanks
> Walter



-- 
Dr. Dmitry Veprintsev
MRC Centre for Protein Engineering
Hill Road
Cambridge CB2 2QH
UK