Interaction of two Cu plasma jets produced successively from the cylindrically shaped massive target

Complete text of publication follows. Our earlier papers demonstrate a very simple method of plasma jet formation, consisting in irradiating a massive planar target of a relatively high atomic number by a partly defocused laser beam. Our present interest is concentrated on interaction of the plasma jet with other media. This paper is aimed at investigations of interaction of two jets launched successively on Cu target. Our attention was paid to the role of radiative cooling in the plasma jet formation. The experiment was carried out at the PALS iodine laser facility. The laser provided a 250-ps (FWHM) pulse with energy of 130 J at the third harmonic frequency (λ3 = 0.438 μm). Two successive jets were produced on a massive flat Cu target provided with a cylindrical channel 5 mm long and 400 μm in diameter. Since the focal spot diameter of the laser beam on the target surface was larger than that of the channel (800 μm), the annular irradiation of the target face resulted in creation of the first plasma jet, whereas the second jet was produced by action of the central part of laser beam on the channel wall. Three-frame interferometric system, x-ray streak camera, and a set of ion collectors were used as diagnostic tools.