We report on the results concerning the characteristics and the
behavior of expanding plasma generated by a Laser Ion Source (LIS). The
LIS technique is an efficient means in producing of multi-charged ions
utilizing pulsed laser beams. In order to extract Cu ions, in this
experiment an XeCl excimer UV laser was employed, providing a power
density on the target surface up to 5 × 108
W/cm2. Two typologies of diagnostic systems were
developed in order to detect the plasma current and the ion energy. The
time-of-flight (TOF) measurements were performed exploiting either a
Faraday cup or an Ion Energy Analyzer (IEA). This latter allowed
getting quantitative information about the relative ion abundances,
their kinetic energy and their charge state. To study the plasma
characteristics we measured the total etched material per pulse at 70
mJ. It was 0.235 μg and the overall degree of ionization, 16%. The
angular distribution of the ablated material was monitored by optical
transmission analysis of the deposited film as a function of the angle
with respect to the normal to the target surface. Applying a high
voltage to an extraction gap a multi-charged ion beam was obtained;
different peaks could be distinguished in the TOF spectrum, resulting
from the separation of ions of hydrogen, adsorbed compounds in the
target and copper.