Strongly localized electric fields were measured in the central cathode helium plasma core region of an inertial electrostatic confinement fusion device by using laser-induced fluorescence (LIF) by the degree of polarization and by the longitudinal alignment methods. Both results show double well potential formation with a slight concave at the center in excellent agreement. The decay time of the excited states is found to indicate least effects by the collisions to ensure the LIF method.