REDUCING FAST IONS IN A PLASMA RADIATION SOURCE HAVING A SECOND ACTIVATION SOURCE

摘要

Reducing Fast Ions in a Plasma Radiation Source A radiation source with an anode and a cathode to create a discharge in a discharge space between the anode and the cathode is disclosed. A plasma is formed in the radiation source which generates electromagnetic radiation, such as EUV radiation. The radiation source includes a first activation source to direct a first energy pulse onto a first spot in the radiation source near the discharge space to create a main plasma channel which triggers the discharge. The radiation source also has a second activation source to direct during the discharge a second energy pulse onto a second spot in the radiation source near the discharge space to create an additional plasma channel. By directing the second energy pulse during the same discharge, a shortcutting of the main plasma current is realized which in turn may reduce the amount of fast ions produced.