Current Status of 14 GHz ECR ion source at CNS, the University of Tokyo

14 GHz Hyper ECR ion source (ECRIS) was first introduced in 1989 at Institute for Nuclear Study, the University of Tokyo. It was relocated to RIKEN Nishina Center in 2004, and has been providing various ion beams to RIKEN AVF cyclotron ever since. Over the course of past thirty years, the performance has been vastly improved. At the moment, it can be operated at high beam intensity to match the requirement of recent experiments, yet further improvement is expected to meet the requirement of higher intensity and more stable operation. In general, the beam intensity is determined by two factors; the amount of ions produced in the ECR plasma and the efficiency of beam extraction from the plasma chamber. In this report, recent research and improvements on both factors will be discussed. (author)