Titanium-based thermal ground plane

Abstract

Titanium-based thermal ground planes are described. A thermal ground plane in accordance with the present invention comprises a titanium substrate comprising a plurality of pillars, wherein the plurality of Ti pillars can be optionally oxidized to form nanostructured titania coated pillars, and a vapor cavity, in communication with the plurality of titanium pillars, for transporting thermal energy from one region of the thermal ground plane to another region of the thermal ground plane.

1 . A thermal ground plane, comprising:
 a wicking structure formed in a titanium substrate, wherein the titanium substrate has a thickness and the thickness is 25 micrometers-500 micrometers; and   a vapor cavity in communication with the wicking structure; wherein:   a fluid contained within the wicking structure and the vapor cavity transports thermal energy between a hotter region of the wicking structure and a colder region of the wicking structure,   the hotter region is hotter than the colder region,   the fluid is driven by capillary forces within the wicking structure, and   the fluid comprises a liquid phase and a vapor phase.   
     
     
         2 . The thermal ground plane of  claim 1 , wherein:
 the wicking structure comprises microfabricated structures and gaps between the microfabricated structures, and   the gaps in the colder region are different from the gaps in the hotter region.   
     
     
         3 . The thermal ground plane of  claim 1 , wherein the wicking structure comprises microfabricated structures and spacings between the microfabricated structures, and the spacings are at least 1 micrometer. 
     
     
         4 . The thermal ground plane of  claim 3 , wherein the microfabricated structures each have a height of 5-200 micrometers and the spacings are 1-500 micrometers. 
     
     
         5 . The thermal ground plane of  claim 3 , wherein the microfabricated structures comprise etched microfabricated structures. 
     
     
         6 . The thermal ground plane of  claim 1 , wherein
 the wicking structure comprises microfabricated structures and gaps between the microfabricated structures, and   and the fluid is transported through the gaps.   
     
     
         7 . A structure comprising:
 a first titanium substrate having a thickness, wherein the thickness is 25 micrometers-500 micrometers; and   a wicking structure formed into the first titanium substrate.   
     
     
         8 . The structure of  claim 16 , wherein the first titanium substrate and the second titanium substrate are welded together to form a hermetically-sealed thermal ground plane. 
     
     
         9 . The structure of  claim 16 , wherein the first titanium substrate and the second titanium substrate are laser welded together to form a hermetically-sealed thermal ground plane. 
     
     
         10 . A method of fabricating a thermal ground plane, comprising:
 forming a wicking structure in a titanium substrate, wherein the titanium substrate has a thickness and the thickness is 25 micrometers-500 micrometers; and   coupling a vapor cavity with the wicking structure;   such that a fluid contained within the wicking structure and the vapor cavity transports thermal energy between a hotter region of the thermal ground plane and a colder region of the thermal ground plane, wherein the hotter region is hotter than the colder region, the fluid is driven by capillary forces within the wicking structure, and the fluid comprises a liquid phase and a vapor phase.   
     
     
         11 . The method of  claim 10 , wherein:
 the wicking structure comprises a plurality of microfabricated structures comprising titanium, and   an etched surface of the microfabricated structures includes a roughness of 1-1000 nanometers.   
     
     
         12 . The method of  claim 10 , wherein:
 the wicking structure comprises microfabricated structures and spacings between the microfabricated structures, and   the spacings are at least 1 micrometer.   
     
     
         13 . The method of  claim 12 , wherein the microfabricated structures each have a height of 5-200 micrometers and the spacings are 1-500 micrometers. 
     
     
         14 . The method of  claim 10 , wherein:
 the wicking structure comprises microfabricated structures and gaps between the microfabricated structures, and   the fluid is transported through the gaps.   
     
     
         15 . The method of  claim 10 , wherein the forming comprises etching. 
     
     
         16 . The structure of  claim 7 , further comprising
 a second titanium substrate;   a vapor cavity formed into the second titanium substrate, wherein the vapor cavity is in communication with the wicking structure; wherein:   a fluid contained within the wicking structure and the vapor cavity transports thermal energy between a hotter region of the wicking structure and a colder region of the wicking structure,   the hotter region is hotter than the colder region,   the fluid is driven by capillary forces within the wicking structure, and   the fluid comprises a liquid phase and a vapor phase.   
     
     
         17 . The structure of  claim 7 , wherein:
 the wicking structure comprises microfabricated structures and spacings between the microfabricated structures, and   the spacings are at least 1 micrometer.   
     
     
         18 . The structure of  claim 17 , wherein the microfabricated structures each have a height of 5-200 micrometers and the spacings are 1-500 micrometers. 
     
     
         19 . The structure of  claim 7 , wherein:
 the wicking structure comprises microfabricated structures and spacings between the microfabricated structures, and   the microfabricated structures comprise etched microfabricated structures.   
     
     
         20 . The manufacture of  claim 19 , wherein an etched surface of the etched microfabricated structures includes a roughness of 1-1000 nanometers.