Inert gas atmosphere replenishment structure
Method and apparatus for replenishing an inert gas atmosphere. A replenishment structure includes a reservoir which encloses an internal inert gas atmosphere. The reservoir has a permeable wall through which inert gas molecules from the internal atmosphere diffuse substantially at a first rate. A control material adjacent the reservoir provides a path through which the inert gas molecules further diffuse substantially at a second rate less than the first rate to replenish a surrounding inert gas atmosphere. The control material preferably surrounds or otherwise confines the reservoir, and diffuses the molecules at a rate selected in relation to which inert gas molecules from a surrounding gas atmosphere escape from a housing in which the replenishment structure is disposed. The permeable wall preferably comprises glass and the inert gas preferably comprises helium. As desired, the inert gas molecules can further be diffused through a second control material to the surrounding atmosphere.
1. A replenishment structure comprising:
a reservoir which encloses an internal inert gas atmosphere and which comprises a permeable wall through which inert gas molecules from said atmosphere diffuse substantially at a first rate; and
a control material adjacent the reservoir through which the inert gas molecules further diffuse substantially at a second rate less than the first rate to replenish a surrounding inert gas atmosphere.
2. The replenishment structure of claim 1 , wherein the second rate of diffusion is substantially selected to match a rate at which inert gas molecules from the surrounding inert gas atmosphere escape from a housing.
3. The replenishment structure of claim 1 , wherein the permeable wall comprises glass.
4. The replenishment structure apparatus of claim 1 , wherein the inert gas molecules comprise helium molecules.
5. The replenishment structure of claim 1 , wherein the control material comprises an epoxy.
6. The replenishment structure of claim 1 , wherein the control material comprises polyimide.
7. The replenishment structure of claim 1 , wherein the control material comprises ethylene vinyl alcohol polymer (EVOH).
8. The replenishment structure of claim 1 , wherein the control material comprises ultra high density polyethylene.
9. The replenishment structure of claim 1 , wherein the reservoir is embedded within the control material.
10. The replenishment structure of claim 1 , further comprising a second control material adjacent the control material and through which the inert gas molecules further diffuse at a third rate less than the first rate to replenish the surrounding inert gas atmosphere.
11. The replenishment structure of claim 1 , further comprising a restriction layer of substantially impermeable material adjacent a portion of the control material, said layer substantially restricting passage of the inert gas molecules therethrough.
12. The replenishment structure of claim 1 in combination with a hermetically sealed housing which encloses the replenishment structure and the surrounding inert gas atmosphere.
13. The combination of claim 12 , wherein the hermetically sealed housing is characterized as a housing of a data storage device and wherein a data recording medium is disposed within the housing.
14. A method comprising:
enclosing an inert gas atmosphere and a replenishment structure within a housing, the replenishment structure comprising a reservoir adjacent a control material, the reservoir having a permeable wall; and
using the replenishment structure to replenish the inert gas atmosphere by diffusing inert gas molecules through the permeable wall at a first rate and then through the control material at a second rate less than the first rate.
15. The method of claim 14 , wherein the using step comprises establishing the second rate of diffusion of the inert gas molecules in relation to a rate at which inert gas molecules of the inert gas atmosphere escape from to housing.
16. The method of claim 14 , wherein the reservoir is characterized as a hollow member and wherein the permeable wall comprises a wall of the reservoir.
17. The method of claim 14 , wherein the replenishment structure of the enclosing step further comprises a second control material through which the inert gas molecules further diffuse to the surrounding atmosphere at a rate less than the first rate.
18. The method of claim 14 , wherein the inert gas molecules of the using step comprise helium molecules.