Interactions between an intense laser pulse and cluster targets are investigated using the recent experimental results of the cluster fusion experiments on the Texas Petawatt Laser (TPW). We achieved about 2x10⁷ DD fusion neutrons per shot on the TPW by optimizing the laser and gas jet parameters. A few different types of cluster targets were used on the TPW including deuterium clusters, deuterated methane clusters, deuterium cluster + helium-3 mixture, and deuterated methane cluster + helium-3 mixture. We designed our own neutron detectors and proton detectors for the measurements of the fusion yields. The calibration method of neutron detectors is described in detail. Through the yield measurements of the 2.45 MeV neutrons from the DD fusion reactions and 14.7 MeV protons from the D-³He fusion reactions in the deuterium-helium-3 mixture target, we successfully measured the ion temperature of the fusion plasma at the time of the fusion reactions. / text