Double Warm Window Conceptual Design Review

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Double Warm WindowConceptual Design Review

• M. Bevins/C. Hutton
• 4/12/06

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CONTENTS

• Objective
• Design Constraints
• Proposed Configuration
• Alternative Window Designs
• Where We Go From Here
• Comments, Concerns, Questions

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OBJECTIVE
Incorporate a second warm window to establish a
UHV waveguide guard vacuum space employing
knife-edge sealing technology in the 12GeV
cryomodule.

• Design efforts began 1/4/06
• Near term goal develop conceptual design by
  4/1/06

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DESIGN CONSTRAINTS
Hard constraint was placed on ability to seal
cavity string vacuum in clean room prior to
assembly into vacuum vessel.
Vacuum Vessel ID
Double-sealing warm window flange required
Limited space requires in-line double-sided
knife-edge window flange.
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DESIGN CONSTRAINTS
Current Warm Window Flange

• Flange is not wide enough to accommodate 2nd
  knife edge.
• Requires change in width of ceramic window OR
  change in width of the flange.
• Strong desire to avoid changes to the RF design
  drove decision to increase the width of the
  flange.

Knife-edge seal to FPC flange
Eyelet Recess
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DESIGN CONSTRAINTS
Maximum Width Dimension for First Window Flange
Renascence FPC 4 5 Spacing

• Driven by spacing between FPCs 4 5
• REN spacing already generates slight interference
  between FPC warm flanges
• Increased FPC 4 5 spacing by trading drift
  length from one end to the other.

12GeV FPC 4 5 Spacing

Increased drift here
Decreased drift here
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PROPOSED CONFIGURATION
Double-Sided Knife-Edge Flange Design

• Design constraints satisfied by modified
  commercial rectangular UHV flange (Thermionics
  Labs)
• Allowed vendor to define the number, size and
  spacing for the bolts and the knife-edge geometry
  - at no cost to us!
• Enabled us to continue with layouts for the
  double window configuration in parallel with the
  flange design.

• Cost for first article 960.00
• Price drops by more than factor of 2 for qty
  above 5

Outside Dimensions 3.78in x 7.62in x 1.36in
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PROPOSED CONFIGURATION
Top hat (instrumentation will have separate
dedicated feed through)
Double-sided window flange
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PROPOSED CONFIGURATION
Flange to 1st (inner) window flange
1-1/3 mini Conflat Inst. Port (IR)
Flange to 2nd (outer) window flange
Cu plated SS Tube (inside dimensions match FPC)
2-3/4 Conflat Vacuum port
1-1/3 mini Conflat Inst. Port (ARC)
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PROPOSED CONFIGURATION

• RF Shield
• Holes bored into wall of waveguide
• Radius inside edge of holes

2.5 OD tube
RF shield holes
Inside weld
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PROPOSED CONFIGURATION
IR sensor
Vacuum pump port
2nd warm window flange
Air side waveguide (same position as SL21)
Arc detector
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PROPOSED CONFIGURATION One Pump per Waveguide
Roughing valve

• Vacuum Analysis
• Desire lt10-8 torr
• System will be baked
• Assumed 2.510-11 torr-liter/s/cm2 outgassing
• Guidance for conductance calcs from J.M.
  Lafferty, Vacuum Science text
• Delivered speed 18 L/s
• Allows for gas load of 210-7 torr-liter/s
  (margin of 5)

30L/s Ion pump
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PROPOSED CONFIGURATION
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PROPOSED CONFIGURATION
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PROPOSED CONFIGURATION
Overall Layout
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PROPOSED CONFIGURATION

• Waveguide support brackets
• Stainless steel construction
• Goal - minimize features that must be controlled
• Provides translation and rotation in all six dof
• Provides allowance for full top hat float

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PROPOSED CONFIGURATION
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PROPOSED CONFIGURATION
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PROPOSED CONFIGURATION
Tunnel Installation

• Module is narrower than CEBAF design
• Complete double window waveguide assembly can be
  installed in test lab

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ALTERNATIVE WINDOW DESIGNS 1 of 2

• Explore brazing eyelet and ceramic into
  stainless steel adapter
• Separates braze and flange sealing challenges
• Adapter would be welded into flange

Ceramic
Eyelet
Double-sided flange
Adapter
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ALTERNATIVE WINDOW DESIGNS 2 of 2
Explore Thermally Matched Tungsten-Copper
Pseudo-Alloy Flange Design

• Methods used in semiconductor industry for many
  years
• Tune WCu CTE by adjusting Cu fraction
• WCu CTE 6.5-8.3 ppm/K (10-20 Cu)
• Alumina CTE 6.7-7.4 ppm/K
• As-sintered hardness gt170 BHN for 20 Cu fraction
  
• Eliminates need for eyelet
• Thermal conductivity gt170 W/m/K
• Material cost per flange 625.00 (430.00 for
  larger qty)
• Very preliminary temperature stress analysis is
  encouraging

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WHERE WE GO FROM HERE

• Procure flanges for testing to evaluate
  rectangular knife-edge sealing reliability
• Complete detail design of waveguide assembly
• Fabricate and test prototype assembly on RF test
  stand (IR camera, vacuum characteristics)
• Fabricate two waveguide assemblies and mating
  dual top hat for HTB testing
• Continue to explore (in parallel with other
  efforts) alternative window designs
• Procure WCu for testing

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COMMENTSCONCERNSQUESTIONS