PURPOSE: To generate high speed neutrons suitable for a research of a material and the like of a nuclear fusion reactor by accelerating a positive and a negative ion in a main accelerator at the same time, and separating an analyzing electromagnet after acceleration.

CONSTITUTION: An ion generated in a positive and a negative ion source 1a, 1b is accelerated up to energy easy to be emitted into a main accelerator 4 in a positive and a negative ion front stage accelerator 2a, 2b, to be implanted into the main accelerator 4 after synthesis in a ? device 3. The main accelerator 4 accelerates the positive and negative ions in a high frequency electric field at the same time. The directions of electromagnetic forces exerted on the positive and negative ions are different from each other in the same magnetic field since the direction of electromagnetic force is dependent on a polarity of electric charge. With this function, the positive and negative ions can be separated from each other. The separated ions independently reach targets 6a, 6b. The single main accelerator 4 irradiates two targets simultaneously, thus generating high speed neutrons at the targets, respectively.