VAKTRAK HomePage

Revision date: 1-MAR-2009

Introduction

Vaktrak is a computer program to calculate equilibrium pressure profiles in conduction limited vacuum systems that uses transfer matrices to model the pressure P and Gasflow Q. The theory is described in SLAC-PUB-5962, which can be downloaded by using the link above. The program VAKTRAK calculates the pressure in a straight system and VAKLOOP in systems made up of links that are straight but can be connected in a network of fairly general topology, such as a vacuum pipe and a parallel pump manifold, connected by small pipes. See the SLAC PUB for details.

Installing the DOS DEMO

The demo runs under DOS or a later derivative thereof (Windows..). Just create a subdirectory, copy the file vaktrak.zip into it and unpack in that directory. If you do not have the unzipper, download the one in the list above.

Using the DOS DEMO

You can download a demo version of the code (limited to 20 elements) by using the link above. It is fairly easy to use. To get a first impression just run the script file RUNVAK.BAT and see what it does. Just remember to use the option [1] when asked about boundary condition and choose not to edit anything when asked later. You'll see pressure profiles interactively, but the graphics is rather clumsy. However, also a file LINK_001.DAT is created with three columns, z-position, pressure, and gas-flow. You can inspect it in your favourite editor or load into your favourite spreadsheet program to display it. The input file is called VAKTRAK.INP, inspect it at your leisure and modify (after making a backup) at your heart's content. Check the SLAC-PUB for details of the input file format.

There is also a demo of the VAKLOOP program, which you can run by executing the RUNLOOP.BAT script. The drill is very much the same, except that there is no question about the boundary conditions and there are a number of files LINK_00n.DAT generated which contain the same information as before (Z,P,Q) in tabular form, ready to feed to a display program. Here the default input file is called VAKLOOP.INP. Have a look at it and play around with it.

Using the Linux DEMO

I have prepared some Linux binaries that you can download from the link on top. The programs are in the file vaktrak_bin.tar and I suggest you unpack them into a directory in your search-path, such as /usr/local/bin or $HOME/bin. The example files that are referenced in a talk are in the archive vaktrak_data.tar . They unpack into a subdirectory named vaktrak. Their use is explained in a talk . Here is just a brief description.

  1. "vaktrak" is a command line program for simple straight vacuum systems. Just start vaktrak with the input file as a command line argument.
  2. "vaktrak_gui" is a graphical application that is wrapped around the normal command line vaktrak code.
  3. "vakloop" is a command line program for multiple connected vacuum system. An example is a parallel pump manifold. Start vakloop with the input file as a command line argument.
The binaries are compile under the KNOPPIX/Debian GNU/Linux system, so if you have some libraries missing, you can find them on any Debian-Linux mirror or at www.debian.org. The KNOPPIX system is a full-grown linux on a single bootable CD, that contains an enormous lot of software (OpenOffice, Mozilla, C and Fortran Compiler, and a LOT MORE). Check it out on www.knopper.net.

Using the KNOPPIX Linux CD with VAKTRAK added

I have prepared a modified KNOPPIX-3.1 CD with the vaktrak binaries and examples from the talk added. I gave this talk during a Course on Vacuum Technology held by Lars Westerberg at Uppsala University and distributed this modified CD there.

The CD is based on a stock-KNOPPIX-3.1 with release date 20.1.2003. I have removed the Talks and Demos directory and some kde help files in some languages and then added vaktrak related material. There are two ways of using the CD. First, just inspect what is on there in a system that is already booted (WIN, MAC, Linux) or second, boot the CD which contains a full grown Linux installation with all bells and whistles.

Using the first alternative, in the root directory of the CD you will find a subdirectory named "vaktrak" that contains the files referenced above DOS and Linux binaries, example files, pdf files of SLAC-PUB-5962 and the talk.

The other alternative is more fun. There you have to configure your PC-computer to boot from CD (usually done in the BIOS startup under Boot Sequence or Boot Order: change from A:,C: to CDROM,C: or something else that starts with CDROM). When you then boot up your PC and the KNOPPIX+VAKTRAK CD is in your CD bay, you will see a boot screen with a command line starting with "boot:". On most desktop computers you can just press "Enter" to continue. If you encounter a problem with that you can restart your computer and press "F2" at the "boot:" prompt to get a brief suggestion what options to choose. I had problems with PCMCIA support on a DELL computer, so I turned it off by doing

boot: knoppix nopcmcia

and pressed "Enter". You can also select the screen resolution and other features. If you have an new Nvidia Graphics card (GeForce4 or so) you may add the following parameter.

boot: knoppix xmodule=nv

Experiment, check the KNOPPIX Web site for help or ask me. Once you passed this stage your system should start up and after a while (30 s on a 2 GHz Pentium4, 10 min on a 75 MHz Pentium1) you should get the start screen of the KDE desktop.

You should be aware that the system runs entirely in RAM, so your hard disk is not touched at all and KNOPPIX does not care what operating system you normally run on that computer. You can see the other harddisk partitions, but they are only visible in read-only mode. So your normal system is safe.

In the startup process KNOPPIX figures out what hardware you have (Soundcard, Graphic card, Network Card) and uses them. If you have for example dynamic IP numbers (DHCP) and your computer is plugged into the network, you can surf right away or copy files to and from other computers using ftp or ssh. KNOPPIX reports the progress of the probing such that you can see what is found or not. At the end of the booting process you get a Desktop which corresponds to the normal Windows desktop, except that it is Linux. A default browser window occupies the DESKTOP which you should close by clicking on the little "x" in the top right corner or use "Location->Exit". Now you have a clean Desktop that looks roughly like this.

Before starting the vacuum softwAre you should adjust your keyboard layout to match your hardware, which is probably a swedish keyboard. You do this by starting the kontrol panel, which is the fifth icon from the left on the task bar on the bottom of the screen. It is the one that looks like a computer screen with a green gadget in front. Simply click on it and after a short while the KDE Control Center will start. On the left hand side you see a list with with various item such as "File Browsing", "Information" and more. You need to select "Peripherials" and then Keyboard. Near the top on the unfolding page page on the right you select the "Primary Layout" to be "Swedish" and click on "Apply" at lower right. Then you can close the Control Center by clicking on the little "x" on the top right.

Now you can start using the vacuum software. You do this by starting a command shell by klicking on the icon that looks like a terminal with a shell (the sixth icon from the left) on the task bar at the bottom of the screen. Once that comes up you need to go to the vaktrak subdirectory by entering "cd vaktrak" and pressing enter. Inspect the contents by entering "ls -l" and pressing enter. It should contain several .vak files and also two .pdf files. Run the vaktrak gui program by entering

vaktrak_gui example1.vak

and press enter. You should see a window with buttons on the top. The input file in the top left and an empty window on the top right and the graphic output window on the lower half of the screen. Press the "Run 0" button near the top of the program and the pressure profile and gas flow should show up on the graphic windows and some diagnostic output in the top right window. You can now start changing the parameters in the input window on the top left and then press on the other run buttons to get extra traces of the profiles with different colors (Run 0=black, 1=red, 2=green, 3=blue) to see how the profiles change and compare them. Once you have reached a satisfactory condition you can press the save button which will write a files named VAKTRAK.TMP which contains your present input configuration. You can also write the profiles as comma separated tables to disk by clicking on the "Action" button and selecting "Traces to File", whence files named #000_p.csv and #000_q.csv are written. Writing files several times will create files with incremented numbers (000 will become 001, 002,...). You can also change the boundary conditions by selecting the desired set under "Boundary Conditions" If input values are reauire you will be propted to enter them.

The files with the data traces can be plotted using for example the spreadsheet application contained in OpenOffice which is installed in the KNOPPIX system. Just click on the icon with the seagulls on the task bar and open .csv files with it.

I have also installed the "vakloop" program on the knoppix disk. You can run it on the command line by entering

vakloop input_file

I have included the VAKLOOP.INP file which is the example from SLAC_PUB_5962. vakloop produces a topdraw file named VAKLOOP.TOP (topdraw is an ancient SLAC graphics format) that you can inspect and possibly extract the relevant information by hand. The other file VAKLOOP.LOG contains some additional info. Unfortunately I have not had the time to merge the vakloop program into the gui, but that will happen as I find some time to do it.

That all for now, folks, but feel free to ask me, if you have questions. I'll update this document as I find necessary. Keep an eye on the revision date at the top.