Abstract An improved version of the radial geometry cesium plasma negative ion source, described by Alton and Blazey, has been designed, evaluated and employed for use during routine operation of the Holifield Heavy Ion Research Facility (HHIRF) tandem accelerator. The mechanical features of the source have been improved to facilitate rapid change of degradable parts such as the sputter probe insulator and cathodes and to provide better thermal isolation of the externally mounted oven from the discharge chamber. The source has demonstrated improved operational stability, higher intensities and increased reliability over its predecessor. Negative ion beams from more than 25 elements have been provided for the HHIRF experimental program including several molecular hydride beams from difficult elements such as Be, Mg, Ti, Sc, Nd and Zr. A detailed description of the mechanical features of the source as well as the negative ion yield dependence on certain operational parameters are presented.