Emission Characteristics and Stability of Laser Ion Sources

A new classification of laser ion sources concerning their pulse-to-pulse reproducibility in the ion emission is proposed. In particular, we distinguish between plasmas according to the electron distribution changing its characteristics at a laser intensity threshold of 10(14) W/cm(2). Well reproducible continuous pulsed ion currents are typical for the intensity below the threshold. In contrast to this plasma the "two-temperature" plasma arising for the intensity above this threshold shows not only a separation of charges in space and time but it also shows irregular and intense outbursts of ions similar to a self pulsing instability leading to a chaos. The sequence of fast ion outbursts visible on time-of-flight spectra is sensitive to details of non-linear interaction of the sub-nanosecond laser beam with the generated plasma.