NetNotes


Edited by Thomas E. Phillips University of Missouri


phillipst@missouri.edu


Selected postings from the Microscopy Listserver from September 1, 2017 to October 31, 2017. Complete listings and subscription information can be obtained at http://www.microscopy.com . Postings may have been edited to conserve space or for clarity.


EM:


wearing a pacemaker while using fi eld Emission SEMs or FIBs I was wondering what experience you have had, of a user with an MRI compatible pacemaker and leads, using and maintaining an electron microscope with ion pumps for the column vacuums? We have a Hitachi S-4700 and a Hitachi FB-2000A from 2003. Is it a big no? Can it be done with a distance from the system maintained, is there any shielding that can be worn or any other concerns that I am forgetting? What issues may be encountered? Pat Scallion pscallio@dal.ca Fri Oct 13 I assume that you are worried about the user and not the


imaging. T e magnetic fi elds around (i.e., outside) the instrument would come primarily from the ion pumps and even those are pretty well contained. Also any stray fi elds are static, i.e., not time varying. T e fi eld levels the user would encounter in an MRI far exceed what you will fi nd around an SEM plus they are repetitive so they would have a much stronger eff ect on the user’s pacemaker. If anything I’d be more worried about the user aff ecting the imaging rather than the SEM aff ecting the user. Henk Colijn colijn.1@osu.edu Sun Oct 15


EM: novel chilled water circulator systems


I have the opportunity to change away from individual chiller units attached to SEMs and TEMs and to work with our physical facilities to design, build, and run something new. I am looking at a single system that will cover multiple microscopes. I am aware of the need for strict temperature control, no vibration, cooling, and pumping redundancy, etc. I wonder if anyone else has gone down this path. Chris Gilpin gilpin@purdue.edu Mon Oct 23


When I visited the JEOL factory, I learned that they had a large water tank on the roof to feed all of the microscopes by gravity. T e only pumping was to pump the “used” water back up to the tank. Because of the large size of the tank, the water temperature had good stability. T ere was no turbulence in the water fl ow, and the overall cost of the system was quite low. John Mardinly john.mardinly@asu.edu Mon Oct 23 We have a building chiller that supplies chilled water for the building temperature control and for heat exchangers used on the microscopes to give us the temperature stability we need. Unless it is oversized, you will not get the temperature stability you require from a building chiller (ours has a 5°F range). Ours is outside so needs to be a 30% glycol/water mixture to survive the Midwest winters. T is has worked reasonably well for us since 1998, however, if, or rather when, the building chiller goes down all of the microscopes go down as well. Alan Nicholls nicholls@uic.edu Mon Oct 23 T is is exactly the type of system I am trying to set up in our building. Do you have any more information you can share on the heat exchanger and how the regulation of temperature is achieved? Ben Micklem ben.micklem@pharm.ox.ac .uk Mon Oct 23 T e units were supplied by Haskris (Model WW2 – water-to- water, non-refrigerated heat exchanger). T ey all have electronic, close temperature control, which has an immersion heater that is used


50


with a modulating water control valve. T e modulating valve varies the fl ow of secondary cooling water to maintain a relatively constant supply water temperature. T e electronically controlled immersion heater switches on and off to compensate for any remaining fl uctua- tions in the supply water temperature, which results in extremely close temperature control. Alan Nicholls nicholls@uic.edu Mon Oct 23 We have such a “shared” cooling system in our CAMCOR facility that supports around 10 beam instruments. http://camcor.uoregon.edu/ . We still have each instrument on its own dedicated water-cooled chiller, but each chiller is cooled by the shared cooling system. T at way we don’t have huge air cooling requirements. T ere is a short discussion of cooling systems here: http://probesoſt ware.com/smf/index.php?topic=951 .0 John Donovan donovan@uoregon.edu Mon Oct 23


Don’t do this. We tried it at ANL, had a special commercial, high-capacity unit designed and built to run all the instruments. Individual units on each instrument, all of them cooled by a central cooling system, is better. When your single cooling water system goes down (and it will), then all instruments are dead in the water. However, if the central chiller that services the small units goes down, it can still be replaced by an emergency house water line. Since the house water line is simply taking away the heat from the regulated individual units (all of which have their own controllers), you can keep all the instru- ments running. T is also holds true for routine servicing. If you need to change a fi lter on your water system, all instruments must be shut down! It was, in my opinion, our only mistake in SAMMLab, and we now essentially use that large single system to cool individual units, which is huge overkill. Two other points: Contamination of the cooling water from all instruments (new and old) gets mixed in the large single system. If one instrument has a problem and contaminates the water, then all instruments get contaminated. Not all instruments run best at the “same temperature.” We have had to tune the water temperature of some units to minimize driſt , and that temperature is a few degrees diff erent than the other microscopes. T is won’t likely be an issue with SEMs, but it can be for HREM/AEMs. Nestor Zaluzec nestor.zaluzec@ gmail.com Tue Oct 24


I second this. ASU had a building-wide recirculation system to separate the chillers from the campus chilled water. When it went down, and it did multiple times, every microscope in the building went down. All FEGs—it was a real pain. John Mardinly john.mardinly@ asu.edu Tue Oct 24


Ditto that and very much so—unless setup includes instant switching to city water in emergency by simply turning a few valves (assuming cooling by city water is suitable…policy, water quality/ temperature, etc.). Vitaly Feingold vitalylazar@att.net Tue Oct 24 I absolutely agree with Nestor. We have a JEOL 1010 TEM and a JEOL 1400 TEM, both on the same larger chiller. To me it is a pain. When the chiller goes out, both TEMs have to be turned off . We just had a power failure in the one TEM room, but since the one chiller is connected to that room, then the chiller went out too. Because of that


doi: 10.1017/S155192951700116X www.microscopy-today.com • 2018 January


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