摘要
It is necessary to develop a series of fission chamber in different sensitivities from high to very low sensitivity for covering the yield range of fusion neutron 10^13～10^21n·s-1 produced by ITER. The high sensitivity fission chamber employs high purity 235U as fissile material, 1 ～ 1.5 g 235U is coated on the multi-electrodes, its structure is shown in Fig. 1 （a）.
