HIGH-DENSITY LITHIUM PLASMA COLUMNS GENERATED BY INTENSE SUBPICOSECOND KRF LASER-PULSES

Subpicosecond KrF laser pulses were focused with an intensity of 2 x 1 0(15) W/cm(2) to a traveling-wave line-focus on solid lithium targets to create a 3 mu m wide plasma column of up to 800 mu m length. The so ft X-ray emission between 1 nm and 15 nm of the laser produced plasma was measured in both longitudinal and transversal directions to the pl asma axis with two single-shot spectrographs. An almost linear increas e of the Li III Ly(alpha)-and Ly(beta)-line intensity with growing pla sma length was observed. An average electron temperature of 35 eV and an electron density of about 1 x 10(21) cm(-3) could be inferred from the lithium spectra. (C) 1998 Elsevier Science B.V.