Energy accuracy and control method of the NV-GSD-HE

The NV-GSD-HE is a high energy ion implanter which has a RF linac acceleration system. The RF acceleration system has many advantages to electro-static acceleration systems in order to obtain high energy ion beams. However, the beam energy from the RF system cannot be determined so easily as the electro-static systems which can determine the beam energy only from voltage(s) supplied to acceleration columns. On the NV-GSD-HE, the Final Energy Magnet is used for energy analysis, measuring its magnetic field strength by a Hall-probe. In order to determine the beam energy by this method, there are some assumptions and the error of each assumption was not so clear. Consequently the final accuracy of beam energy of the NV-GSD-HE was not so clearly defined. At the same time a control method of the accuracy was not found. In this study, each component of error is investigated and the total accuracy of energy is estimated. Additionally, a method of controlling accuracy is proposed.