Discharge lamp comprising coated electrode
A discharge lamp ( 1 ) comprising a discharge vessel ( 4 ), at least one electrode ( 22, 24 ) arranged within the discharge vessel, wherein at least parts of the electrode ( 22 ) are provided with a particle composite coating ( 32 ) made up of a matrix layer and particles embedded in the matrix layer, wherein the extinction coefficient k of the material for the matrix layer is less than 0.1 in the spectral range between 600 nm and 2 μm, and wherein the extinction coefficient k of the material for the particles is greater than 0.1 in the spectral range between 600 nm and 2 μm.
1. A discharge lamp comprising:
a discharge vessel; and
at least an anode arranged within the discharge vessel,
wherein at least parts of the anode are provided with a particle composite coating comprising a matrix layer and tungsten particles embedded in the matrix layer,
wherein the proportion by volume of the tungsten particles lies in the range between 2 and 50%,
wherein the extinction coefficient k of the material for the matrix layer is less than 0.1 in the spectral range between 600 nm and 2 μm,
wherein the extinction coefficient k of the material for the particles is greater than 0.1 in the spectral range between 600 nm and 2 μm, and
wherein the discharge lamp is a short-arc discharge lamp configured for direct current (DC) operation.
2. The discharge lamp as claimed in claim 1 , wherein the extinction coefficient k of the material for the matrix layer is less than 0.01 in the spectral range between 400 nm and 8 μm.
3. The discharge lamp as claimed in claim 1 , wherein the matrix layer consists of one or more elements from the following group: oxides, carbides, nitrides, fluorides.
4. The discharge lamp as claimed in claim 3 , wherein the matrix layer consists of one or more elements from the following group: ZrO2, MgF2, SiC, AIN.
5. The discharge lamp as claimed in claim 4 , wherein Y2O3 and/or MgO is added to the matrix layer.
6. The discharge lamp as claimed in claim 1 , wherein the thickness of the matrix layer lies in the range between 1 micrometer and 1 millimeter.
7. The discharge lamp as claimed in claim 1 , wherein the grain size of the particles lies in the range between 20 nm and the thickness of the matrix layer.
8. The discharge lamp as claimed in claim 1 , wherein a region of the anode which is directly struck by radiation emitted in a plasma arc when the lamp is in operation is not coated.
9. The discharge lamp as claimed in claim 1 , wherein the proportion by volume of the tungsten particles lies in the range between 5 and 30%.
10. The discharge lamp as claimed in claim 1 , wherein the proportion by volume of the tungsten particles lies in the range between 5 and 15%.