A Proposed Layout for Light-Sealing A Proposed Layout for Light-Sealing around the Focal Planearound the Focal Plane

Robert Besuner

17 April 2005

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Some notesSome notes

• Desire is to replace two or three labyrinths with one.—Labyrinths replaced: cone/OTA, cone/FP, maybe FP/aft of FP.

—Replace those with one light seal from radiator to OTA.

• Could substitute word ‘labyrinth’ with ‘bellows’ or anything light-tight with minimal thermal and mechanical coupling between the two sides.

• Relative motions between radiator and OTA in vibe may be large...labyrinth clearances here are 20mm.

• Thermal coupling across labyrinth could be sizeable. One possibility is to make light seal thermally insulation. If G-10 fiberglass, something like a watt might flow from OTA to radiator (That’s pure conduction, no rad. analysis at labyrinth).

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Fully assembledFully assembled

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light seal cover removedlight seal cover removed

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fp light seal being withdrawnfp light seal being withdrawn

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light seal turned to view labyrinthlight seal turned to view labyrinth

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fp, cone installedfp, cone installed

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fp being removed, should use GSE to support fp being removed, should use GSE to support bipodsbipods

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fp removed, cone still installedfp removed, cone still installed

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cone being withdrawn, note mounting ring that cone being withdrawn, note mounting ring that stays with bipods, which stay with benchstays with bipods, which stay with bench

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cone and fp removed, the cone’s ring and bipods staycone and fp removed, the cone’s ring and bipods stay

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section showing possible heat strap pathssection showing possible heat strap paths

• violet-straight to cover, heat flows from cover to rest of radiator

• blue-straight to (conducting) light seal, heat flows to main radiator and cover

• green-thru light seal (thru labyrinth?, thru more strap terminations?), then to radiator

• Also, note gap between cone and cold plate...no labyrinth