Dewar Vessel Assembly
Vacuum-Jacketed Cryogenic Dewar Vessel
Double-walled vacuum-jacketed stainless steel dewar vessels forming the primary physical containment boundary for cryogenic biological samples at 77 K
Purpose
Provide mechanically robust, vacuum-insulated containment vessels that maintain structural integrity for 100+ years while minimizing parasitic heat leak and supporting internal cold bus, rack, and LN2 reservoir integration
Context
Each dewar is an independent pressure/vacuum boundary. The inner vessel operates at 77 K containing LN2 and sample racks; the outer vessel is at ambient lunar temperature. The annular vacuum space contains MLI and getter materials. Dewars are sized to hold a fractional partition of the 6.7M species collection, with minimum 4 independent units for fault isolation. Loss of vacuum in one dewar triggers autonomous sample transfer protocols.
Principles
- ▸Double-walled vacuum-jacketed construction eliminates convective heat transfer and minimizes conduction
- ▸Stainless steel 316L provides excellent cryogenic toughness — no ductile-to-brittle transition above 77 K
- ▸Getter materials (barium, titanium) maintain vacuum quality by adsorbing residual outgassing over decades
- ▸Dewar neck tube geometry (length-to-diameter ratio) is the primary determinant of parasitic conduction heat leak
- ▸Pressure relief valves on both inner vessel and vacuum jacket prevent catastrophic overpressurization
Typical implementations
- ▸MVE Variō series large-capacity biobank dewars (stainless inner/outer, MLI in annulus)
- ▸Taylor-Wharton K-series transport dewars with impact-resistant outer shells
- ▸Custom CERN/Fermilab cryostat vessels with electropolished inner surfaces for cleanliness
- ▸Bayonet-mount cold bus penetrations for removable cryocooler interfaces
Lunar considerations
- ▸Lunar ambient vacuum (~10^-12 torr) naturally maintains jacket vacuum — no active pumping needed
- ▸Launch vibration loads (up to 10g) require structural reinforcement beyond static design
- ▸1/6 g affects LN2 sloshing modes and liquid-vapor interface management inside dewars
- ▸Micrometeorite shielding (Whipple bumper) required if any outer vessel surface is exposed
- ▸Thermal contraction differential between inner (77 K) and outer (~100 K PSR) vessels requires flexible mounting
Specifications
Functional
| primary function | Provide vacuum-insulated containment for cryogenic sample storage at 77 K |
| inputs | LN2 from L2-CRY-LN2 via bayonet fill/drain connections, Refrigeration from L2-CRY-COOL via cold bus penetrations, Sample racks from L3-CRY-TANK-RACK for internal mounting |
| outputs | Stable 77 K internal environment for sample preservation, Parasitic heat load specification to L2-CRY-COOL (target <0.5 W per dewar), Structural support for internal rack assemblies and cold buses |
| inner vessel temperature k | 77 |
| heat leak per dewar w | <0.5 (excluding access port openings) |
| vacuum jacket pressure torr | <1e-5 (maintained by getters) |
| design pressure inner bar | 3 |
| burst pressure inner bar | 12 |
| design life years | 100 |
| number of dewars | minimum 4 independent units |
Physical
| dimensions | TBD — estimated 1.5m diameter x 2.5m height per unit |
| materials | Stainless steel 316L (inner vessel, electropolished), Stainless steel 304L (outer vessel), Barium/titanium getter strips (vacuum maintenance), Indium wire seals (vacuum-tight flanges), G-10 fiberglass composite (low-conductivity support struts) |
| inner temperature k | 77 |
| outer temperature k | 40-100 (PSR ambient) |
| vacuum jacket | Lunar ambient vacuum, supplemented by getters |
| radiation | Shielded by vault structure and regolith |
Operational
| power consumption w | 0 |
| thermal range c | -196, -170 |
| lifetime years | 100 |
Interfaces
Provides
- Internal mounting rails and thermal anchoring points for sample rack assemblies
- Cold bus penetration flanges for cryocooler thermal coupling
- Bayonet fill/drain ports and internal LN2 reservoir volume
- Neck tube and flange interface for sample access port assembly
Requires
- MLI blankets and vapor-cooled shields installed in vacuum annulus
- Vault floor mounting, vibration isolation pads, and seismic restraints
- Temperature sensors, vacuum gauges, and strain gauges on vessel walls
Cite this entry
Lunar Ark Codex. "Dewar Vessel Assembly" (L3-CRY-TANK-DEW). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-CRY-TANK-DEW
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.