Study On Production Of Highly Charged Ions With Auxiliary Electron Injection Into ECR Ion Sources

Developed in late 1960 s, Electron Cyclotron Resonance ion source(ECRIS)is a new type of positive ion beam generator. Because of its broad ion variety, good quality, long duration, high stability and repeat-ability, etc., ECR ion source is considered to be one of the most effective facilities to generate high-current highly charged ion beams. However, because of the limitation of high-frequency microwave and superconductor technique, the development of ECRIS reaches its bottleneck. In this case, other ways to improve the performance of ECRIS is well needed.As described in this article, we inject electron beam into ECR chamber by using electron gun. First, we calculate the distribution of magnetic field of the experimental platform——the ECRIS using evaporative cooling technique(LECR4), estimate the motivation of electrons in chamber. Based on this estimation, we design the structure of the electron gun which reaches both requirements of experimental and engineering after assessing the key parameter of the electron beam. According to a great deal of simulations aim on different working position of electron gun, it is proved that the effect of injection and protection of cathode can’t be guaranteed at the same time. We choose a safe position in order to protect the cathode, simulate the path of electron in the chamber.We modify the original injection component of LECR4 to make sure the electron gun fit for LECR4, solving the problem of mobilization and providing potential at the same time by a clever design. During the experiment on LECR4, the magnetic induction intensity and the energy of the electron beam are chosen to be the keyparameter to hold and change. Two groups of experiment based on low frequency microwave and low injection of electron is planned. It is proved that under the condition of certain magnetic induction intensity of the axial magnetic mirror field, a pulsing leap status alternates a direct status of the current of the extracting ion beam is observed when the electron’s energy is above 1800 e V. In the mean time, the top of the pulse and the average current of the ion beam rises, the ionization state moves to a higher level. This phenomenon can be turned on and off by controlling the experimental condition. At the last part of the article, we discuss this improvement of the current and charge state of the ion beam despite of the position’s missing between the injection of electron beam and the resonance surface, and hold the opinion that this phenomenon is positive to both pulsed and direct beam,reflect on the defect of the experiment and come up with several ways to improve, hoping for better researching results.