22 A beam production of the uniform negative ions in the JT-60 negative ion source

摘要

In order to improve the spatial uniformity of the negative ion beam and to produce high current negative ion beams in a large negative ion source, a magnetic field configuration is modified from an original transverse filter to a tent-shaped filter, in combination with reducing the magnetic field strength in the JT-60 negative ion source. As a result, the beam uniformity is improved from 68% to 83% over an area of the whole extraction area of 450 x 1100 mm(2). The improvement of the beam uniformity leads to the production of 32A H- ion beams with the whole extraction area. The obtained beam current fulfills the requirement for JT-60SA. (C) 2015 Elsevier B.V. All rights reserved.