NetNotes


and see vacuum rated red and tan tubing. (I have no idea what the color means. For reference, the tubing that came with the SEM was black.) T e tan jumps from 3/4" with 5/8" walls to 1" with 1/2" walls. T e red does come in 7/8" but it has 1/2" walls too. I’m not even sure if that would fi t out the opening in the back of the SEM. T ere's a good chance the vacuum hose is original to the scope, which is a Leica S430. Any help would be appreciated. Am I correct in assuming the hose should be replaced? Ryan rdpierce@pobox.com Tue Jan 27 A good “standard” supplier is http://duniway.com/catalog/ su-tubing-clamps.php (many components, not just the hose). A cheap option is more work but you can make whatever diameter hose plus it can be easily compressed around a (much) smaller diameter tube since the support spring is separate. Components: a) braided PVC of suitable diameter, either Home Depot etc. or McMaster Carr; b) continuous spring for supporting hose from collapsing, Again McMaster Carr. Tubing: http:// www.mcmaster.com/#standard-high-pressure-pvc-tubing/=vnotog then select “clear” or from home page enter “High-Pressure PVC Tubing” in search line, then select “clear” spring: http://www.mcmaster.com/#cut- to-length-springs/=vnp0wo then select “extension spring” or from home page enter “Cut-to-Length Extension Springs” stainless springs soſt er and won't rust. T ey are sold in 20" pieces and will easily extend 10+ times. Springs made with wire 0.04" to 0.08" thick are best for diameters around 1". 3/4" to 1" ID vac. hose made in this fashion costs between $2 and $5 per foot depending on source of materials. It is transparent so oil accumulation can be seen before problems begin, plus PVC will outlast rubber hands down. T e oldest still in use I installed in 1998. Use standard common hose-clams as long as they fl at and at least close to 1/2" wide. Wire clamps not recommended. T in-wall-soſt -not-braided low pressure PVC is even cheaper but less durable and unforgiving with regard to vacuum leaks at installation. Same longevity unless stressed. For long straight connections use large diameter thin-wall copper tube, again from Home Depot, just ensure adequate cross-section for very long connections. Vitaly Feingold vitalylazar@att.net Wed Jan 28


If you make a cut through the tubing, you should be able to measure ID and OD accurately. Bill Tivol wtivol@sbcglobal.net Wed Jan 28


SEM: power supply board failure


We have a JEOL 6100 that needs its magnifi cation power supply board replaced. Our chiller stopped working the other day for about an hour and the mag. power supply got so hot half of the wires melted. We are trying to repair it in house but it’s not looking good. It would be greatly appreciated if anyone can suggest a source for either repairing or replacing it. T e JEOL 6100 model is SM111040-154. T e power supply model is SM111040-7A. Rod Rowland rowland@matsys.com Fri Jan 16 According with my experience, you’ll have to change this power supply because it’s hard to repair when such problem occurs. T is part contains many power transistors and, for this reason, is water cooled. T e most common accident occurs when water continues to fl ow in the hose when power is switched off —the gradient between room temperature and the cooling water temperature can cause condensation of water from air humidity on the surface of the power supply components and circuitry, which then short-circuits when the power supply is switched back on. Week-end and holidays are dangerous periods where the SEM is shut down but not the water cooling supply. Normally there is a small detector that shut off the board when temperatures exceed 70°; it seems this security has not worked for your SEM or this was shorted in the past. It’s very easy to do from outside of the board and very easy to forget later. Probably JEOL has no spare parts because the JSM 6100 is rather old. Another solution is to fi nd this part from a scrapped 6100. T ere is currently a 6100 on EBay for 12000 dollars. Last solution is to change


66


all the broken parts of the board. T is is possible for a good electronics engineer if you can supply him the diagrams. Nicolas Stephant nicolas. stephant@univ-nantes.fr Tue Jan 20


SEM: beam alignment problem


We cannot align the aperture in our JSM5600LV SEM. Using the wobbler tool we cannot correct horizontal movement, in all 3 aperture positions. It looks like the alignment point lies outside the aperture openings. T e problem worsens with increasing tilt angle and aff ects the resolution; 5K looks like 15K. I cleaned the upper column up to the aperture level and the aperture, but didn’t help. It was not dirty anyway. However, last time I changed fi lament I noticed some little white crisps around the Wehnelt orifi ce. Is it likely to have contamination of the lower parts of the column or something else? Yorgos Nikas eikonika@ otenet.gr T u Jan 22


I don’t expect the dirt on the Wehnelt aperture to be much of a problem, but better clean it away. Are you sure your fi nal aperture strip (or do you have single apertures?) are not moving in the aperture strip-holder? Did you check that the holder is perfectly clean? Since you say you have the same problem with all three aperture openings it might also be a problem with the astigmatism correction voltage going to the coils. If you have the schematics, you can measure this at the plug. Stefan Diller stefan.diller@t-online.de T u Jan 22 May I suggest you take out the aperture strip and see if you can align the instrument to your satisfaction? The problem may be in another part of the column resulting in an apparent aperture problem. I too do not expect the dirt on the Wehnelt to be a real problem. Try this and let us know what happens. You will need to use small spot sizes to obtain a reasonable image quality in the test. Steve Chapman protrain@emcourses.com Thu Jan 22


SEM: Wehnelt aperture sizes


Has anyone with a LEO/Zeiss 1455VP LaB 6 SEM compared the Wehnelt aperture sizes? T ey are 1mm and 500um. Zeiss seems to have settled on the 500um Wehnelt aperture size for LaB 6 and W emitters. Is there any feedback from users about which aperture size produces the best results? Gary Gaugler gary@gaugler.com Fri Feb 20 Wehnelt apertures are usually selected depending upon the application. High magnifi cation operations are best made with a small aperture, with the fi lament closer to the front of the Wehnelt, whereas for low magnifi cation work, moving the fi lament back, and using a larger aperture, provides suffi cient performance with longer fi lament life. T ose carrying out a large amount of BSE investiga- tions will also be better served using a larger aperture as bigger sources provide higher signals. Most manufacturers use a smaller Wehnelt aperture than for tungsten, when LaB 6 fi laments are fi tted, as stronger bias fi elds are required to control the source. Steve Chapman protrain@emcourses.com Tue Feb 24


SEM-EDS: analysis of Pb


I have several copper-tin-lead alloy standards with varying Pb contents (5, 10, 15, 20). I analyzed them by the SEM-EDS, but it keeps giving me lower Pb concentrations (around 2, 5, 7, 10 individually). T e totals are good around 100 percent, but just inaccurate (tin is the same, but Pb is lower and Cu is higher than their real values. I use the default internal calibration (leaded glass) to calibrate Pb element. It is known that Pb in the copper alloy will form a separate phase. Has anyone encountered this problem and how did you solve it? Gary sniper711220@hotmail.com Fri Jan 30


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