FEI engineer scheduled a service session to change TEM filament yesterday. Everything went smoothly, but he could not get the beam this morning. I took the filament out and checked it, but could not find anything wrong. He will continue to test it today.
TEM down on 5/20/2015 and up on 6/5/2015
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The TEM is up now. I have run the TEM for several hours this afternoon. TEM alignment, settings and camera are checked Ok. You may start to use it from now on. Please pay attention on a few things. The new filament is different from the old one. The filament limit setting is 25 and emission setting is 1 for 200kV and 2 for 80 kV. Please do not change the setting for filament limit and emission, otherwise, the filament can be damaged easily. HT instability can be seen occasionally. If the HT drops to 0. You may wait for a couple of minutes and turn on HT again. The HT should become more and more stable with using time.
The HT at 200kV dropped to 0 during last evening. It is reconditioned to 200kV again. Electron beam was seen, but it is not so stable. It seems that the gun is still degassing. A brief alignment was done. The TEM setting was checked. CCD camera was tested as well, It seems that the TEM is ready to use when the beam is a little more stable.
HT reached to 200kV yesterday, but it was not stable. The HT dropped from 200kV to 0 in last night. Continue conditioning the HT today. I hope that the TEM may be up tomorrow.
I conditioned the HT up to 190kV yesterday. The HT was not stable at 190kV so it was dropped to 175kV for overnight. I will continue to condition the HT and hope that the it can be stable at 200kV today. Then TEM alignmen, settings and CCD camera will be checked.
The HT was conditioned up to 185kV this morning. There was a power outage at about 1:30pm and the TEM was shut down. After finishing a SEM training session, I started pumping the TEM …It could take a few hours to pump the system down. I hope that good vacuum can be achieved tomorrow morning and then HT conditioning may start again.
The FEI engineer replaced the old filament with a new one successfully on May 28 and conditioned the TEM up to 180kV. He continued to condition the TEM on May 29. The high tension reached to 200kV but not stable. The TEM will be pumped through the weekend. I may check the TEM in the weekend or Monday.
A senior FEI engineer arrived to check the filament issue.
After FEI engineer left our TEM lab last Friday, I monitored the TEM. The vacuum was gradually recovered in the long weekend. I started to condition the HT on Monday. I started HT at 120 kV and reached 170kV. Yesterday, I continued to condition the HT till 9pm and reached 190kV. I saw illumination at 80kV and 160kV and aligned the TEM. It seems to me that there was lots of gas absorbed in the gun ( maybe because the gun was open for several times). So before further conditioning today, I want to run the TEM at 80 or 160 kV to heat up the filament and get rid of the absorbed gas and meanwhile give students a training.