6132009

1
Ptube Design Aspects

• Aluminum versus stainless steel
• Stainless will avoid oxidation patch breakdown
  at high rate?gain
• We should procure a hot Ruthenium source to test
  aluminum at high rate.
• We could contemplate 1/64 walls to save on
  weight and material costs
• Either one can be extruded with same difficulty
  and expense
• Thin walled stainless much tougher to retro
  machine.
• Choice of wire diameter
• 90 ? dia wire was choice of SDC since easier to
  string (more visible)
• Because of tension-area scaling, dia irrelevant
  to gravity sag and EM stability
• Appears that no wire support will be necessary
• Higher diameter means higher voltage (Harder to
  distribute and avoid corona)
• Larger diameter means a steeper log(gain) versus
  V/VT curve
• More critical operation according to Sauli

2
Thoughts on gas flow

• Parallel versus series gas distribution
• A parallel gas flow may be more efficient but it
  might be more complicated to establish the two
  pressure reservoirs.
• A series (serpentine) flow may require different
  end cap designs which could double our mold cost.
• But probably 2 designs necessary because
  electronics only mounts on one end.
• Are gas leaks necessary to maintain flow in
  serpentine design?

3
Preliminary thoughts on End Cap design

• The end cap which holds the wires also acts as
  the gas manifold.
• Manifold is in a channel below pins.
• Serpentine gas flow design with gas injection on
  every other tube. Opposite on other end.
• End cap injection molded plastic with several
  pulls to create cavities
• Actual brass crimp pin is held in by a delrin
  insert to avoid charge buildup
• Rounded edges avoid corona
• Free space above the pins to mount electronics
• Placement of gas inlet is a concern.

• If the end cap must serve a double layer of
  tubes, price will increase significantly