Effect of neutral beam quality on design of window in bending system

The structure of neutral beam injector on EAST is introduced. Neutral beam usually contains three kinds of high-energy ions, which do not lost charge in the neutralizer. Taking a deuterium beam with energy of 80 keV as a reference beam, the paper calculates radius of ions with different energy and explains the section extension. As a result, three dimension relation of window in bending system is given. Then, principle of the cause of divergence angle is described. Effect of divergence angle on design of window in bending system is analyzed. The result and analysis illustrate that dimension of entrance window and return window have the same numerical value as that of beam. When relative position and dimension between entrance window and return window is reasonable, energy deposition at inj