The generation of deuteron beam from a 3 kJ Mather type plasma focus is studied. Two simple ion collectors made of copper plates are employed and are placed at the axis of the electrodes to detect the ion beam. The deuteron beam intensity at various deuterium gas pressures is determined together with ion beam energy using the time of flight method. For a series of discharges of the present plasma focus system operated at 15 kV discharge voltage, ion beams of energies ranging from 50 to 200 keV have been measured. The suitable deuterium filling pressure for ion beam production for electrodes lengths of 16 cm, 22 cm and 27 cm are 1 mbar, 0.7 mbar and 0.5 mbar respectively.