ECR multi-charged ion source directly excited in a circular TE01 mode cavity resonator

A new concept is proposed for enhancing the efficiency of an electron cyclotron resonance (ECR) plasma for production of multi-charged ions (TAIKOII). The plasma chamber is a circular cavity resonator with two metal plates. A fixed plate is installed at the tip of the ion extractor. The distance between the fixed plate and the antenna installed at the side wall is equal to a quarter of the guided wavelength λg for the circular TE01 mode microwave. A mobile plate is inserted from the opposite side along the geometrical axis to tune the microwave. Excitation of single TE01 mode has been confirmed. The electric field has only a circumferential component and is axially symmetric in the same direction as electron cyclotron motion. The peak value of the electric field is located at the ECR zone. Multi-charged ions are extracted by a voltage of 10 kV and the charge state distribution (CSD) of their ion currents are measured by using the sector magnet and the faraday cap. The extracted Ar4+ ion current changes periodically when the mobile plate moves in the plasma and the interval of the mobile and the fixed plates is several times λg/2 in the TE01 mode microwaves. We present and discuss production of multi-charged ions by applying the TE01 mode microwave in order to enhance efficiency of the ECR in the optimized magnetic field.