Example of a melted RF seal:
Example of a melted RF seal Inside of ring These Cu fingers are brazed onto the SS mounting plate
RF seal from Arc 7:
RF seal from Arc 7 Inside of ring
Slide5:
These omega fingers are over crushed Melted the Ag plating Ag melts at 1200 deg C
and boils at 2400 deg C
Some Numbers:
Some Numbers Each arc has 32 cells. Each cell has a bellows module with 2 RF seals and a zero length bellows with one RF seal.
Arc 9
11 cells worth of bellows and flex flange RF seals checked
All bellows ok
3 flex flange RF seals melted
Arc 7
18 cells worth of bellows and flex flange RF seals checked (8 cells checked in July of these 8 four were rechecked)
3 bellows replaced in July
1 bellows found with several disconnected fingers
1 bellows found with 1-2 displaced fingers
2 flex flange RF seals melted
Arc 1 (Have some evidence of a problem but have not looked here yet)
No problems with any of the RF seals at the bellows
Mechanics:
Mechanics Plan View The zero length bellows is located on the long ~6 m dipole chamber where it attaches to the quadrupole chamber
New Designs:
New Designs 1. Same as the old design but omega fingers made out of Ag or Au plated Inconel
2. New “J” type finger attached to one side only New design
Summary:
Summary In looking for bad bellows we have uncovered a problem with some of the RF seals at the flex flange in the HER
So far we have found 5 bad seals out of a total of 87 inspected. We have looked at 29 of the type that have failed.
We also suspect a problem with either a bellows or an RF seal in arc 1 but have not looked there yet
We have enough seals to replace all the damaged ones we have found and we are working on two different upgrade designs
We are also investigating the possibility of installing a thermocouple at the flex flange seal