Hello there! I study communications engineering and got really fascinated by magnetic fields. I started to do my own bit of "research" or "further understanding" how magnets work, how the field is influenced and what can the field influence. After doing so I got fascinated by particle accelerators and especially the quadrupole magnets to adjust and focus the beam. Now I'd like to do some research on those magnets. The only way to get a direct visual feedback is to build a small particle accelerator with a low pressure hydrogen atmosphere to make the beam visible like in the "Fadenstrahlröhre" (Sorry, I don't know the english word for it: Wikipedia Picture). So what I thought I'd do is accelerating the electrons with about 200 to 400 Volt. To achieve the visibility of the beam, I need a tube that won't break when evacuated. I could do that by myself but I have no oven that big to reduce the tension after sealing the tube. So I need to buy a presealed tube that has already been tempered. I have found many stores but theynever had a tube longer than 1 meter that could withstand a vacuum (these had been designed to be filled with inert gases). Anyone know a source?