Laser produced plasma light source having a target material coated on a cylindrically-symmetric element
The present disclosure is directed to laser produced plasma light sources having a target material, such as Xenon, that is coated on the outer surface of a drum. Embodiments include bearing systems for rotating the drum that have structures for reducing leakage of contaminant material and/or bearing gas into the LPP chamber. Injection systems are disclosed for coating and replenishing target material on the drum. Wiper systems are disclosed for preparing the target material surface on the drum, e.g. smoothing the target material surface. Systems for cooling and maintaining the temperature of the drum and a housing overlying the drum are also disclosed.
1. A device comprising:
a stator body;
a cylindrically-symmetric element rotatable about an axis and having a surface coated with plasma-forming target material for irradiation by a drive laser to produce plasma in a laser produced plasma (LPP) chamber, the element extending from a first end to a second end;
a gas bearing assembly coupling the first end of the cylindrically-symmetric element to the stator body, the gas bearing assembly establishing a bearing gas flow and having a system reducing leakage of bearing gas into the LPP chamber by introducing a barrier gas into a first space in fluid communication with the bearing gas flow; and
a second bearing assembly coupling the second end of the cylindrically-symmetric element to the stator body, the second bearing having a system reducing leakage of contaminant material from the second bearing into the LPP chamber by introducing a barrier gas into a second space in fluid communication with the second bearing.
2. The device of claim 1 , wherein the second bearing assembly is a magnetic bearing and the contaminant material comprises contaminants generated by the magnetic bearing.
3. The device of claim 1 , wherein the second bearing assembly is a greased bearing and the contaminant material comprises contaminants generated by the greased bearing.
4. The device of claim 1 , wherein the second bearing assembly is a gas bearing assembly and the contaminant material is bearing gas.
5. The device of claim 1 , wherein the cylindrically-symmetric element is mounted on a spindle and the system reducing leakage of bearing gas into the LPP chamber comprises a first annular groove, in one of the stator body and the spindle, in fluid communication with the first space and arranged to vent the bearing gas, at a first pressure, from a first portion of the first space; a second annular groove, in one of the stator body and the spindle, in fluid communication with the first space and arranged to transport a barrier gas, at a second pressure, into a second portion of the first space; and, a third annular groove, in one of the stator body and the spindle, in fluid communication with the first space, the third annular groove disposed between the first and second annular grooves in an axial direction parallel to the axis; and, arranged to transport the bearing gas and the barrier gas out of a third portion of the first space to create, in the third portion, a third pressure less than the first pressure and the second pressure.
6. The device of claim 1 , wherein the cylindrically-symmetric element is mounted on a spindle and the system reducing leakage of contaminant material into the LPP chamber comprises a first annular groove, in one of the stator body and the spindle, in fluid communication with the first space and arranged to vent contaminant material, at a first pressure, from a first portion of the first space; a second annular groove, in one of the stator body and the spindle, in fluid communication with the first space and arranged to transport a barrier gas, at a second pressure, into a second portion of the first space; and, a third annular groove, in one of the stator body and the spindle, in fluid communication with the first space, the third annular groove disposed between the first and second annular grooves in an axial direction parallel to the axis; and, arranged to transport the contaminant material and the barrier gas out of a third portion of the first space to create, in the third portion, a third pressure less than the first pressure and the second pressure.
7. The device of claim 1 , further comprising a drive unit at the first end of the cylindrically-symmetric element, the drive unit having a linear motor assembly for translating the cylindrically-symmetric element along the axis and a rotary motor for rotating the cylindrically-symmetric element about the axis.
8. The device of claim 1 , wherein the plasma-forming target material in Xenon ice.
9. The device of claim 1 , wherein the bearing gas is selected from the group of gasses consisting of Nitrogen, Oxygen, purified air, Xenon, and Argon.
10. The device of claim 1 , wherein the barrier gas is selected from the group of gasses consisting of Xenon and Argon.