Simple emittance measurement of H(sup -) beams from a large plasma source

摘要

An emittance meter is developed using pepper-pot method. Kapton foils are used to detect intensity distributions of small beamlets at the 'image' plane of the pepper-pot. Emittance of H(sup -) beams from a large plasma source for the neutral beam injector of the Large Helical Device (LHD) has been measured. The normalized emittance (95%) of a 6 mA H(sup -) beam with emission current density of about 10 mA/cm(sup 2) is (approx)0.59 mm mrad. The present system is very simple, and it eliminates many complexities of the existing schemes. (author).