Method and device for cooling a gas

Abstract

The invention relates to a method and to a device for the vibration-free cooling of a gas. In a first cooling step, the gas is brought into thermal contact with a first cooling medium. In a second cooling step, it then flows through a liquefier, which is in thermal contact with a second cooling medium, and is thereby cooled by no more than 10 K. This low temperature gradient is primarily responsible for the gaseous or liquid gas flow exiting the liquefier being highly homogeneous and laminar. It is therefore suited for further processing into a flow of solid pellets having consistent size. These pellets can be transported across several meters in a vacuum and are therefore suited as a target material for generating a plasma by way of intensive laser radiation.

1 . A method for cooling a gas comprising the following steps:
 in a first cooling step, the gas is conducted through a line which is in thermal contact with a first cooling medium;   in a second cooling step, the gas is conducted through a liquefier which is in thermal contact with a second cooling medium, and in the process is cooled by no more than twice the temperature difference between the melting point thereof and the boiling point thereof.   
   
   
       2 . The method according to  claim 1 , wherein, in the second step, the gas is cooled by no more than 1.5 times the temperature difference between the melting point thereof and the boiling point thereof. 
   
   
       3 . A method according to  claim 1 , wherein the second cooling medium is colder than the first. 
   
   
       4 . A method according to  claim 1 , wherein a liquefied cryogas, which can exchange vapor with the surrounding area, is selected as the first cooling medium. 
   
   
       5 . A method according to  claim 1 , wherein the second cooling medium is conducted through the liquefier. 
   
   
       6 . The method according to  claim 5 , wherein the gas and the second cooling medium are conducted in opposite directions through the liquefier. 
   
   
       7 . A method according to  claim 1 , wherein a gaseous second cooling medium is selected. 
   
   
       8 . A method according to  claim 5 , wherein prior to entering the liquefier, in an intermediate cooler, the gas is brought into thermal contact with the second cooling medium exiting the liquefier. 
   
   
       9 . A method according to  claim 8 , wherein the gas is heated between the first cooling step and the intermediate cooler. 
   
   
       10 . A method according to  claim 1 , wherein the gas is liquefied in the second cooling step. 
   
   
       11 . The method according to  claim 10 , wherein the liquefied gas is conducted through a vibrating nozzle. 
   
   
       12 . The method according to  claim 11 , wherein the nozzle vibrates parallel to the direction of flow of the liquefied gas. 
   
   
       13 . The method according to  claim 12 , wherein the nozzle vibrates with an amplitude between 100 and 1000 nm. 
   
   
       14 . A method according to  claim 11 , wherein the liquefied gas is transferred from the vibrating nozzle into a vacuum. 
   
   
       15 . The method according to  claim 14 , wherein the liquefied gas is solidified during the transfer into the vacuum. 
   
   
       16 . A method according to  claim 14 , wherein the transfer into the vacuum takes place at a distance from the vibrating nozzle. 
   
   
       17 . A method according to  claim 14 , wherein the liquefied gas is transferred into the vacuum by way of a chamber, in which the same gas is present in a gaseous state. 
   
   
       18 . The method according to  claim 17 , wherein the gas in the chamber is close to the triple point. 
   
   
       19 . A method according to  claim 14 , wherein the liquefied gas is transferred through a nozzle into the vacuum, the internal diameter of the nozzle steadily decreasing toward the vacuum. 
   
   
       20 . The method according to  claim 19 , wherein the internal diameter of the nozzle upon entry of the gas is greater by a factor of no more than 10 than on the vacuum side. 
   
   
       21 . A method according to  claim 14 , wherein the gas is transferred into the vacuum in at least two stages. 
   
   
       22 . The method according to  claim 21 , wherein in the first stage, a pressure of 10 −5  mbar or more, preferably of 10 −4  mbar or more, is present. 
   
   
       23 . A method according to  claim 21 , wherein in the last stage, a pressure of 10 −6  mbar or less, preferably of 10 −7  mbar or less, is present. 
   
   
       24 . A method according to  claim 14 , wherein after the transfer into the vacuum, the gas has a velocity of at least 50 m/s, and preferably at least 100 m/s. 
   
   
       25 . A method according to  claim 1 , wherein at least one gas from the group (He, N 2 , Ar, Kr, Xe) is selected as the cooling agent. 
   
   
       26 . A device for cooling a gas, comprising a liquefier comprising at least two lines, through which the gas and a primary cooling medium can flow in opposite directions, and which are in thermal contact with each other. 
   
   
       27 . The device according to  claim 26 , wherein the two lines are disposed parallel to each other. 
   
   
       28 . A device according to  claim 26 , wherein the two lines are disposed concentrically with respect to each other. 
   
   
       29 . A device according to  claim 26 , comprising a pre-cooling medium disposed upstream of the liquefier, wherein the medium can be brought into thermal contact with the gas. 
   
   
       30 . The device according to  claim 29 , wherein the pre-cooling medium is disposed in a receptacle, which is traversed by a line through which the gas can flow. 
   
   
       31 . The device according to  claim 30 , wherein the receptacle is a ring-shaped container. 
   
   
       32 . A device according to  claim 30 , wherein a supply of the second cooling medium is disposed in the region defined by the receptacle. 
   
   
       33 . A device according to  claim 26 , further comprising a nozzle, which is disposed downstream of the liquefier and comprises means for generating a vibration. 
   
   
       34 . The device according to  claim 33 , comprising a piezoelectric means for generating the vibration. 
   
   
       35 . A device according to  claim 33 , comprising at least one vacuum chamber disposed downstream of the nozzle. 
   
   
       36 . The device according to  claim 35 , comprising plural vacuum chambers disposed one after the other and having graduated pressures. 
   
   
       37 . A device according to  claim 35 , wherein the vacuum chamber is disposed at a spatial distance from the nozzle. 
   
   
       38 . The device according to  claim 37 , comprising a triple point chamber as a means for disposing the vacuum chamber at a distance from the nozzle. 
   
   
       39 . A device according to  claim 35 , wherein an inlet into the vacuum chamber is configured as a further nozzle, the internal diameter of which decreases steadily in the direction of the vacuum. 
   
   
       40 . A device according to  claim 39 , wherein the internal diameter of the further nozzle on the inlet side is greater by a factor of no more than 10 than on the vacuum side. 
   
   
       41 . A plasma source comprising a radiation source directed at the interaction zone, comprising a device according to  claim 26 , which is disposed in such a way that it is able to output cooled gas into the interaction zone. 
   
   
       42 . A plasma source according to  claim 41 , comprising a laser as the radiation source. 
   
   
       43 . A plasma source according to  claim 41 , comprising a cooling trap for receiving gas, which does not interact with the beam from the radiation source. 
   
   
       44 . A device for the photolithographic structuring of semi-conductors comprising a plasma source according to  claim 41 . 
   
   
       45 . A particle accelerator comprising a plasma source according to  claim 41 .