Some notes on MAT 253 source cleaning. For disassembly we used the PowerPoint slides from A.Michaud as a general guide. ******************** An issue arose during reassembly that's important enough to mention first. THE WIRE LEAD FROM THE PIN 1 FEEDTHROUGH MUST BE CONNECTED TO THE ELECTRON COLLECTOR *BEFORE* THE COLLECTOR IS ATTACHED TO THE IONIZATION HOUSING. Turns out the wire lead, as a spring, has a rather anemic force constant. Thus if the lead is attached after the collector is attached to the housing, it is reluctant to remain in place. It may hang in empty space, or yield a short circuit by touching a frame post or the flight tube wall when the springs are compressed. ******************** Some part numbers: -tungsten cathode filament (1) 067 2460, ~385 -halogen source heater lamps (2) 108 5040, ~$5 -gold gasket, ion source, Thermo, 055 1600, ~$1000 -gold gasket, ion source SIS, custom sizes - too small OD - 4.5 ID x 0.031 in. (114.3 ID x 0.79 mm) -> ~115.9 OD 4.5 ID x 0.040 in. (114.3 ID x 1.02 mm) -> ~116.3 OD SIS now carrying items with Thermo dimensions - 117.5 ID x 115.5 x 1 mm 455160, $996 -quartz rings, thin 35.6x30x2 (2) 078 3930, ~$130 -quartz rings, med 35.6x30x5 (4) 078 3920, ~$287 -quartz ring, thick 35.6x30x10 (1) 078 3910, ~$383 -quartz tube, inlet 4x2x23 078 3900, ~$170 -ceramic rod, primary lenses (4) 043 9530, ~$155 -ceramic spacers: -elec collector 3.9x2.2x2 (2) 056 1180, ~$11 -ion source base 4x2.1x10 (2) 056 0570, ~$10 -ion source base 6x4.2x4 (4) 056 0780, ~$35 -einzel lens 6x4.2x4 (8) 056 0780, ~$35 (12) total -einzel lens 4x2.1x8 (4) 056 0760, ~$35 Basic Strategery (sic, SNL): -Consult the MAT 253 operating manual for additional information -Disassemble -Clean all parts in the ultrasonic bath with cyclohexane. Allow to fully evaporate afterward -If properly clean, cyclohexane will leave absolutely NO residue when evaporated. Consider using already used slightly dirty hexane for an initial cleaning of the filthier parts -Clean all metal parts in the ultrasonic bath with RBS 35 cleaner. Do NOT put the ceramic or quartz parts here. Rinse with DI water -Anneal quartz spacer rings and ceramic insulators -Remove vapor deposited metal from metal parts and the ceramic rods with 600 grit sandpaper or alumina powder. Next time try 1500 grit Rinse with DI water and dry with acetone -Remove vapor deposited metal from ceramic parts with a diamond file. Rinse with DI water and dry with acetone The ceramic parts are *relatively* inexpensive. Consider replacing them Warnings from the manual: -Do not anneal ceramic parts with metal i.e. the rods -Do not use ultrasonic cleaning on the source magnets -Do not use RBS cleaner on anything but stainless steel parts -Do not use RBS cleaner on any quartz or ceramic parts -Remove the focusing plates without tilting them relative to the support rod, to avoid metal abrasion onto the rods Warning from experience: -Do not use ultrasonic cleaning on the exit slit. Last time that popped a spot weld, and fixed by Kris/TSA -When annealing the quartz spacer rings, place them on their sides, resting flat in the muffle furnace to avoid breakage ******************** -First, fully open the "sulfur window," else the ion source assembly cannot be removed. We're about 0 for 8 on that here. No harm done if we don't pull too hard before we realize our mistake... -The ceramic spacers are relatively inexpensive. Suggested is to replace them with new. They are tiny and removing vapor deposited metal with a diamond file as in the manual would be tedious -The ceramic rods are a special case because of the metal fitting fused to one end. Again, DO NOT anneal the ceramic rods. Sonicate with cyclohexane. If metal vapor deposition discoloration can be seen, sand lightly with 600 paper. Rinse repeatedly with warm water and then DI water. Dry with acetone -The two permanent magnets are each inscribed with both N and S. When assembled, on the electron emitter side the S will be visible, and on the electron collector side the N will be visible. FOCUSING LENS plates are all engraved with numbers to help keep them in order Split lens plates are engraved on both halves All engraved numbers on lenses 1-9 between the support plate and the ionization housing should face ionization housing, and if upright, on the left Einzel lens 04 engraved numbers also face ionization housing, so that the terminals angle toward the flange Einzel lens grounding plates 03 and 05 were facing the opposite direction when disassembled. For these the orientation doesn't matter We suspect that the grounding plate numbers 03 and 05 were also facing the ionization housing when the unit was first disassembled Viewed from the downstream emitter end- Einzel lenses, outside the exit slit - all are split in half 05 grounding plates, no leads, grounded through support pins and frame 04 with a lead to each half 03 grounding plates, no leads, grounded through support pins and frame Again, only the 04 lenses have engraved numbers facing the base Key to numbers engraved on the parts 1 ion source base S window 2 grounding plate 3 y-deflection split lens 4 "lens" 5 r-deflection 6 y-deflection split lens 7 shield 8 extraction 9 cover plate ionization housing Reassemble onto the ion source base, with the gas inlet port to the right. The engraved numbers should be visible, facing you, upright, and to the left. Split lenses have both halves engraved - see PA010037.JPG and PA010042.JPG. Photo PA010034_Lens9- The "6" in this photo should be a 9, the last lens the rests directly on the ionization housing Photo PA010039_lens6- The split ring welded to the back of #6 halves goes into the thickest of the quartz spacers behind it Key to feedthrough map in manual 1 electron collector 2 ionization housing 3 lens 8 4 empty space 5 lens 7 6 split lens 6 7 split lens 6 8 lens 5 9 split lens 3 10 split lens 3 11 Einzel lens 4 12 Einzel lens 4 13 bulb 14 both bulbs 15 bulb -gold gasket wire dia. 0.031 in. -gold gasket dia. 118mm PN 0551600, $1020 from Thermo. These may be reused many times if the flange bolts are not overtightened. Tighten just enough to pull a vacuum in the range of 1.5-2.5e-08 millitorr. -gold gasket dia. 4.5in = 114.3mm, $442 from SISWeb.com. Not sure if these will work. We will certainly give it a try next time since we already bought one and the original is at the end of its life, i.e. has been squashed too flat to seal well again, with bolts fully tightened. Continuity check - before final tightening of the flange bolts, perform the following check of the feedthrough pins with an Ohmmeter or continuity checker. ALL PINS MUST BE ISOLATED FROM THE INSTRUMENT FRAME/GROUND. -Pins 1-12 should be isolated from *everything* -Pins 13, 14, and 15 are for the source the heater lamps. Since the bulbs are present when assembled, there should be conductance among all three pins, and nowhere else. -Pins K+ and K- should of course conduct through the tungsten filament, and nowhere else.