摘要
The target of nuclear fusion research is to realize effective and sustainable fusion reaction of hydrogen isotope ions and to get the thermonuclear energy economically. Naturally the parameters of plasma ions are of importance and measurement of the parameters of ions has been an essential concern to the nuclear fusion research work since 1950s. However, the ions are confined by the mag- netic field, one can measure the neutral particles emitting from the plasma to obtain the parameters of ions. The diagnosing of neutral particles is a method by measuring the neutral particles from the plasma to obtain the information （such as energy） of ions, and it is important and foundational to the experi ments as well.
