Heat pipe, lithographic apparatus and device manufacturing method

Abstract

A heat pipe to maintain an object at a substantially uniform temperature is disclosed. The heat pipe includes a chamber containing a liquid reservoir and a vapor space, part of the chamber being defined by a condensing surface, and a liquid transporter to apply a force additional to gravity to liquid to transport liquid away from the condensing surface towards the reservoir, wherein the condensing surface is shaped such that condensed liquid moves along it towards the liquid transporter.

1 . A heat pipe to maintain an object at a substantially uniform temperature, comprising:
 a chamber containing a liquid reservoir and a vapor space, part of the chamber being defined by a condensing surface; and   a liquid transporter to apply a force additional to gravity to liquid to transport liquid away from the condensing surface towards the reservoir,   wherein the condensing surface is shaped such that condensed liquid moves along it towards the liquid transporter.   
     
     
         2 . The heat pipe of  claim 1 , wherein the condensing surface is shaped such that condensed liquid moves along it towards the liquid transporter under gravity. 
     
     
         3 . The heat pipe of  claim 1 , wherein the condensing surface is shaped such that condensed liquid moves along it towards the liquid transporter under a surface-tension drainage force. 
     
     
         4 . The heat pipe of  claim 3 , wherein the condensing surface has a local radius of curvature which decreases in a direction towards the liquid transporter. 
     
     
         5 . The heat pipe of  claim 3 , wherein the condensing surface is shaped that a surface-tension drainage force at one location is in a different direction to a surface-tension drainage force at another location. 
     
     
         6 . The heat pipe of  claim 3 , wherein the condensing surface is formed into a plurality of ridges and grooves. 
     
     
         7 . The heat pipe of  claim 1 , wherein the liquid transporter is configured to apply the force to the liquid by capillary action. 
     
     
         8 . The heat pipe of  claim 1 , wherein the liquid transporter has an end in the reservoir. 
     
     
         9 . The heat pipe of  claim 1 , wherein a projection projects from the condensing surface towards the liquid transporter. 
     
     
         10 . The heat pipe of  claim 1 , wherein a gap exists between the liquid transporter and the condensing surface. 
     
     
         11 . The heat pipe of  claim 1 , wherein material of the liquid transporter has substantially the same coefficient of thermal expansion as material of walls defining the chamber, and the liquid transporter extends between a bottom surface of the chamber defining the reservoir and the condensing surface. 
     
     
         12 . The heat pipe of  claim 1 , wherein the liquid transporter is in the form of a plurality of projections extending towards the condensing surface from the reservoir. 
     
     
         13 . The heat pipe of  claim 1 , further comprising a structural member extending between the condensing surface and a bottom wall of the chamber opposite the condensing surface. 
     
     
         14 . The heat pipe of  claim 1 , wherein the liquid transporter and/or a structural member comprises a gap for the passage of vapor therethrough. 
     
     
         15 . A heat pipe to maintain an object at a substantially uniform temperature, comprising:
 a chamber containing a liquid reservoir and a vapor space, part of the chamber being defined by a condensing surface; and   a liquid transporter to apply a force to liquid to transport liquid away from the condensing surface towards the reservoir,   wherein the condensing surface has projections that project down towards the top of a liquid transporter.   
     
     
         16 . The heat pipe of  claim 15 , wherein the condensing surface is curved such that its surface changes its angle smoothly from being horizontal at a position between adjacent liquid transporters to being at an angle to horizontal closer to the liquid transporters. 
     
     
         17 . A heat pipe to maintain an object at a substantially uniform temperature, wherein the heat pipe comprises a chamber defining a liquid reservoir and a vapor space, part of the chamber being defined by a condensing surface, the condensing surface shaped such that acceleration of the object applies a force to liquid on the condensing surface to return the liquid to the liquid reservoir. 
     
     
         18 . The heat pipe of  claim 17 , wherein the liquid is returned via a liquid transporter and the force is a force in the direction of the liquid transporter. 
     
     
         19 . The heat pipe of  claim 17 , wherein the liquid makes a static contact angle to the condensing surface of greater than 90°. 
     
     
         20 . A heat pipe to maintain an object at a substantially uniform temperature, wherein the heat pipe comprises a chamber defining a liquid reservoir and a vapor space, part of the chamber being defined by a condensing surface to which liquid in the liquid reservoir has a static contact angle of greater than 90°.