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Ultra fast ion shutter employing a laser-produced plasma

In order to protect a multilayer mirror from sputtering or ion implantation, high-energy ions ejected from EUV source plasma are to be blocked. We propose use of a laser-produced plasma as an ultra-fast shutter. Ion signal form an ion-source plasma dropped abruptly by two orders of magnitude to a noise level after the shutter plasma generation. The stopping effect for the high-energy ions was observed to reduce as the distance of shutter plasma expansion increases, but the suppression of ions below detection level was observed up to 10 mm. We concluded that reduction of ion signal was caused by in-take of the source plasma flow into the stream of the shutter plasma.