A method for stabilizing a plasma is disclosed. The method includes (a) providing in an ionization chamber a number of high voltage wires and a gas suitable for forming a plasma, and (b) exposing the gas to a high voltage thereby igniting the gas to form the plasma. Upon ignition, the plasma is subjected to an amount of light. A use of the method to generate X-rays is also disclosed. The invention is further directed to an ionization chamber including (a) a gas suitable for forming a plasma, and (b) a number of high voltage wires for exposing the gas to a high voltage thereby igniting the gas to form the plasma. The ionization chamber includes a device for subjecting the plasma upon ignition to an amount of light. The invention relates to an X-ray generator including such ionization chamber and to a laser apparatus including such X-ray generator.

A method for detecting particles in a gas of a process environment present in a process chamber, the method comprising the steps of: guiding the gas with the particles into an ionization and charging unit (11) being in fluid communication with the process chamber, wherein the ionization and charging unit has an anode (12) and a cathode (13) and is adapted and configured to at least partly ionize said gas and to charge at least some of said particles; igniting and sustaining a discharge in said gas by applying a voltage between said anode and said cathode of the ionization and charging unit; measuring a current flowing from or to the anode and/or from and to the cathode; detecting the particles based on an AC component or a transient of the measured current. The invention is further directed to an apparatus for detecting particles, to a coating system comprising such an apparatus and to a use of ionization unit.