I.)18-25mm Phosphor Coated Tubing
Note: We recommend the following procedure to remove moisture from large diameter tubing before bombarding.
A.) Tightly close main and vacuum gauge stopcocks.
B.) Seal unit(s) onto manifold.
C.) Open main stopcock and pump unit(s) down to 20 microns, roughly 2 minutes if you do not have a vacuum gauge. Open vacuum gauge stopcock and check vacuum.
D.) Completely close main stopcock, vacuum gauge stopcock and stopcock on oil manometer (if you have one).
E.) Backfill with 3½ Torr (mechanical gauge) 3½ mm (oil manometer) of air. This can be done by pinching a piece of clean, dry blow hose about two inches away from where it is attached to the air admittance stopcock. Now quickly open and close the stopcock and adjust pressure to 3 ½ Torr (3 ½ mm). This can be done by opening the main stopcock to reduce pressure, or repeating blow hose procedure to increase pressure.
F.) With main stopcock closed and bombarder at lowest setting, switch on bombarder and immediately increase current to 450mA. (Note: If arc can’t be struck, slightly reduce pressure in unit by quickly opening main stopcock with bombarder off).
G.) With main stopcock closed, continue bombarding until glass temperature reaches 100C (212F). Try to maintain an average pressure of 4.5 Torr, (no less than 3 Torr and no greater than 7 Torr).
H.) At this point, if you are using an oil manometer, open stopcock on manometer and then open main stopcock and vacuum gauge. If you do not use an oil manometer, then simply open main stopcock and vacuum gauge.
I.) Let unit(s) pump down to at least 10 microns or less and cool to approximately 70C (158F).
J.) This completes the PREHEATING process and you are now ready to bombard the unit(s).
II.)Bombarding EGL 19CL Electrodes
Note: If you have completed PREHEATING process, proceed to A. If not, you must first seal unit(s) onto manifold, and pump unit(s) down to 20 microns (about 2 minutes if you don’t have a gauge) and then proceed to A.
A.) Completely close main stopcock, vacuum gauge stopcock, and oil manometer stopcock.
B.) Backfill unit(s) with 4 Torr (mechanical gauge) 4mm (oil manometer) of air. This can be done by pinching a piece of clean, dry blow hose about 2 inches away from where it is attached to the air admittance stopcock. See Section E under PREHEATING for details.
C.) With the main stopcock, vacuum gauge stopcock, and oil manometer stopcock completely closed, switch on bombarder at lowest setting and immediately increase to 400 – 500mA. (Note: If arc can’t be struck, slightly reduce pressure in unit). See section E under PREHEATING for details.
D.) Maintain pressure in unit(s) between 4 and 5 Torr (4 and 5mm). Note: When opening and closing main stopcock to remove accumulated pressure, be sure to switch off bombarder before opening main stopcock to prevent flashback.
E.) Continue bombarding until glass temperature reaches 160C(320F). At this point reduce and maintain pressure in unit(s) to 1½ Torr (1½ mm) and increase the bombarding current to 750-800 mA making sure to stop bombarding when you open the main stopcock to prevent flashback.
F.) Continue bombarding until glass temperature has reached 250C (482F), and the electrode shells have been heated to a bright red/orange over their entire length.
G.) Switch off bombarder, open stopcock on oil manometer (if you use one) and open main stopcock. After about 30 seconds open stopcock on vacuum gauge and pump unit down to ultimate vacuum of system. (We recommend 1 micron or less).
H.) When units have cooled to approximately 40C (104F), close main stopcock, vacuum gauge stopcock and oil manometer stopcock (if you use one).
I.) You may now fill unit(s) to proper pressure and seal off.
Note: These are guidelines only, and may be affected by atmospheric conditions, size of glass being pumped, bombarder voltage, and vacuum pump efficiency. With Mercury still in the trap, switch on unit for 5 minutes on a 30 milliamp transformer. Turn switch off and allow the units to cool to room temperature before rolling the mercury from the trap into the unit. Carefully seal the tubulation off by slowly heating and pulling the trap away not allowing the glass to collapse and create a stress seal which can crack at a later time. Roll the mercury through the unit insuring that it reaches both electrodes and age the unit face side up for at least 1 hour. We recommend that a 30 milliamp transformer be used for the initial stage of the aging process to enable any trace amount of impurities caused by sealing off the mercury trap to be absorbed by the interior components. The unit can be switched to a larger transformer for aging after this process. It is a common process to age 1 or 2 units on a large transformer. This method causes too high an operating current initiallyfor a new unit. If larger transformers are used for aging, then footage of tubing closer to the recommended amount the transformer is rated for should be connected during this period. Allow your pump to warm up for 1 hour prior to processing. You must service your pump regularly, changing the oil and opening the gas ballast to regenerate the oil by expelling condensed vapors. Keep your manifold clean and free from any contaminants such as grease, glass particles and mercury.