Soft X-ray plasma source for atmospheric-pressure microscopy, radiobiologyand other applications

A large-volume non-conventional XeCl excimer laser (Hercules) emitting long pulses (from 10 ns up to 120 ns at a wavelength of 308 nm) has been used t o drive a soft X-ray plasma source. The X-rays pulse duration and the energ y conversion efficiency in different spectral regions have been measured; X -rays emission lasting up to 100 ns has been obtained in the 70 eV region. The dependence of X-ray pulse duration on the size of the laser spot is dis cussed. The X-ray source can be operated both in vacuum and in helium at at mospheric pressure. This allows irradiating over a large area both for cont act microscopy of living specimens (up to 1 mm(2) windows) and for radiobio logy (up to few cm(2) windows). The experimental results obtained for these two applications as well as for radiographic images of living insects are discussed.