An extreme-ultraviolet (EUV) radiation source near the 13-nm wavelength generated in a small (1.1 J) pinch plasma is presented. The ignition of the plasma occurs in a pseudosparklike electrode geometry, which allows for omitting a switch between the storage capacity and the electrode system and for low inductive coupling of the electrically stored energy to the plasma. Thus energies of only a few joules are sufficient to create current pulses in the range of several kiloamperes, which lead to a compression and a heating of the plasmas to electron densities of more than 1017 cm−3 and temperatures of several tens of electron volts, which is necessary for emission in the EUV range. As an example, the emission spectrum of an oxygen plasma in the 11–18-nm range is presented. Transitions of beryllium- and lithium-like oxygen ions can be identified. Current waveform and time-resolved measurements of the EUV emission are discussed. In initial experiments a repetitive operation at nearly 0.2 kHz could be demonstrated. Additionally, the broadband emission of a xenon plasma generated in a 2.2-J discharge is presented.
© 1999 Optical Society of America
(220.3740) Optical design and fabrication : Lithography
(260.7200) Physical optics : Ultraviolet, extreme
(300.6560) Spectroscopy : Spectroscopy, x-ray
(350.5400) Other areas of optics : Plasmas
Klaus Bergmann, Guido Schriever, Oliver Rosier, Martin Müller, Willi Neff, and Rainer Lebert, "Highly Repetitive, Extreme-Ultraviolet Radiation Source Based on a Gas-Discharge Plasma," Appl. Opt. 38, 5413-5417 (1999)