Conversation with Jay Bookbinder, 7/22/99

Dr. Jay Bookbinder

SAO

60 Garden St.

Cambridge, MA 02138

617 496-7577 (fax)

617 495-7058 (phone)

I had a long conversation with Jay Bookbinder about the Al filters and Clamshell. Here are the notes I made in random order (before I forget). They built the filters & clamshell for Trace and are providing them for the SXT on Solar-B.

  1. He offered to help in any way he could, including building some of the parts for us.
  2. They launched the trace filters under vacuum. “Clamshell” actually had 3 doors, a circular domed front door and two D-shaped rear doors. The vacuum req’t was ???, with a hold time of 21 days. The doors had wax actuators (Starsys) & springs. The front door was opened first and the rear doors 2 weeks later after outgassing. The actuator has a wedge device to break loose a stuck O-ring seal.
  3. Door actuators were one-shot.
  4. Front door was domed, ~1 cm thick, ribbed to lighten.
  5. The reason for vacuum was acoustics. High freq vibrations are not much of a problem as the filters have very low mass. The J-side is providing them a spec for acoustics ~140dB very soon.
  6. They measured filter temps in solar simulator & saw 110 – 150C
  7. Ask for filters “hung loose” if possible – different thermal expansion of Al frame vs Ni mesh
  8. Frame is anodized Al, with separate clamping frame. 3 screws mounting for each frame.
  9. Large filters are much more fragile than small. Avoid gusts of wind etc.
  10. Store in vacuum or dry nitrogen. Vacuum is best. Oxidation?
  11. They made lots of special tools, shields, and storage containers to protect filters. (sneeze guards etc.)
  12. Plexiglas covers, breather holes
  13. Use captive screws
  14. Taped screwdrivers etc. so they can’t go through holes far enough to touch filter.
  15. Their req’t for blocking white light was 10^-4
  16. Need sunshield covering filter frames.
  17. They need to be grounded. They pick up static charge & dust clings.
  18. Make sure shake fixture enclosure is clean – dust will kill filter. Shake EM filter before FM filter to prove fixture is OK.
  19. The clamshell needs an air leak around filter.
  20. Pressure gauge needed. Calibration was a problem with the one they used.
  21. Pump slowly, vent slowly. Sintered metal vent restrictor/filter.
  22. WAG: flight filters $5K ea, engineering filters ~$2.5K ea.
  23. They studied blackening the mesh, and carbon coating the Al, but abandoned that. Carbon thick enough to change  was too thick to transmit the EUV.
  24. They had 3 flight filters, 3 flight spares, and 2 engineering filters that were good enough to fly.
  25. Debris on orbit is a risk you take. They had a focal plane filter, so they could tolerate a few pinholes.
  26. If the Japanese use very pure hydrazine for the thrusters, the exhaust products are not too harmful. The filter stays hot so the junk will cook off.
  27. They vacuum baked the filters to remove water, but found that the glue outgassed forever. Eventually you would bake out the glue entirely. They use a relatively short bake, and wait 2 weeks before opening the rear doors.
  28. Trace was in an Al tube, the Solar-B SXT will use a composite tube.
  29. They built a facility for a solar simulator & light leak tester.