How to get localhost and username within IDL.

To get the localhost name and username within idl, you can use the get_login_info function.


IDL>help,/str, get_login_info()

** Structure <88f5c88>, 2 tags, length=24, data length=24, refs=1:

   MACHINE_NAME    STRING    'PSGJPENDLETON'

   USER_NAME       STRING    'jimp'

How does a cryo-pump work?

Previously, I have discussed the cryotorr 8, but how does it work?
A small presentation is shown at the helix website. The cryo-pump uses helium as cooling agent. It cryo-condenses water, nitrogen and argon by frosting them on the condensation array. By using activated charcoal, it cryo-adsorbs hydrogen, helium and neon. Water is cryo-condensed on the first stage array, at ~65K. Nitrogen and argon are cryo-condensed on the second stage at ~12K. Hydrogen, helium and neon are cryo-adsorbed also on the second stage.
 By cryo-pumping, we are able to lower the pressure to ~3e-11 Torr from 8e-11 Torr.

If there is no gas load, what is the lowest of the cryotorr 8 cryo-pump?

Following the previous post, you have installed a new cryo pump cryotorr 8 from Brooks Automation, P/N 8033170. However, the lowest temperature you get after the bake is ~13K, which is almost the same you've reached with the previous cryo-pump.
Shouldn't be lower?
Talking to the technical support, GUTS, the cryo-pump temperature of the second stage should be ~11K. However,  it could be easily 1K off and even up to 2K because the silicon diode thermometer is not calibrated. There is no clear-cut reason for a ~13K reading instead of ~11K. It could be due to the calibration curve, or it could be due to a tiny leak. I strongly recommend you to rule out the last possibility by performing an extensive leak-check.
 In the case of the second option,  where you do not have a calibration curve for the  thermometer, it is important how you read the temperature. Brooks automation recommends using a Brooks temperature indicator, P/N 8043459G001; it comes with a "standard" calibration curve. If you are using a Lakeshore 211 temperature controller, it has three different standard calibration curves corresponding to dt470, dt670 and CTI silicon diodes. You can test the display reading of a Brooks temperature indicator against the Lakeshore 211; when the Lakeshore 211 using the CTI calibration curve displays 13.4K, the Brooks temperature indicator will display 12.9K.

Plotting scientific graphs directly in latex

Previously, I have introduced the latex compiler for text formatting. By using the tikz package; its manual can be found in the CTAN site and here there are some examples.  Pgfplots packages uses tikz to plot scientific data (manual).

My cryo-pump has reduced its performance; its operational temperature and base pressure are higher. Why?

Just to restate the issue: the cryo-pump is connected to a chamber, let's say through a gate valve; after the bake the chamber is at 7e-11 Torr and the cryo-pump operational temperature is at 13.4K. You have leak checked the pump and it is ok. When you open the gate valve, the cryo-pump temperature increases to 14K and the chamber pressure drops only to 5.5e-11 Torr. Eventually it gets to 3.5e-11 Torr. However, the pump temperature slowly increases.

You've got the cryo-pump model: CryoTorr 8 and looked at the cryo-pump manual on the troubleshooting chapter, just to realize that your problem is not described there.

Then you go to the compressor manual with the compressor model: 8200. You check that the compressor static pressure of 250 psi is in the specified range: between 245 and 255 psi. Also, the nominal compressor pressure pulses between 280 and 285 psi which is also within the range given by the manual: 280 and 285psi. Finally you verify the compressor draws 7.95 A which is within the working conditions of the compressor: between 8 and 9A.

After you call the GUTS technical service (24/7/365) from Brooks Automation. They explain you that the average lifetime of the pump is around 5 years; a reduced performance is expected after this. When you give your serial number, you are pointed out that your pump is around 7 years old. These symptoms point to a seals wear off inside the cold head. The solution: either exchange the pump  or send it to them. In any case you will get a refurbished one.

Interactive science simulations

The university of colorado at Boulder has developed interdisciplinary researched-based  science simulations: PhET. They are useful to introduce different concepts but, in my opinion, they should not replace the much richer learning process through direct experience.
 Have fun!

Como dividir y multiplicar tan solo sabiendo sumar, restar y la tabla del dos

Este es un interesante capitulo del libro de Adrian Paenza sobre como multiplicar o dividir dos numeros cualquiera tan solo sabiendo sumar, restar y la tabla del dos.

Recommended earthquake safety procedures for BC, Canada

Last week was the BC shakeout: an awareness day for safety procedures during an earthquake. The basic steps are drop, cover, and hold on. A more comprehensive guide can be found on the Seven steps to earthquake safety and UBC emergency procedures for an earthquake. If you are indoors, they resume to drop, cover, and hold on.
You can check  the latest shake status for Canada here. The issue around Vancouver is that the tectonic plates are stuck so if there is a considerable earthquake it will be a big one.