Strong heating and improved confinement of ions have been observed in an axisymmetric magnetic mirror field supplemented with an electrostatic DC field across and along the magnetic field lines. The increased life time of ions is understood as trapping of ions in the electrostatic potential well in the magnetic mirror field. The efficient heating of ions results from thermalization through weak collisions and/or finite correlation time of the strong E*B type instabilities excited by the radial current flowing into the outer electrode. The ion temperature increases in proportion to VH2, the square of the applied DC voltage for heating.