Conceptual Design for a Fast Neutron Ionization Chamber for Fusion Reactor Plasma Diagnostics

A conceptual design for a radiation-hard “pointing” fast neutron ionization chamber that is capable of delivering a 1 MHz countrate of T(D,n) events at ITER is given. The detector will use a ∼1 cm³ volume of CO₂ fill gas at 0.1 bar pressure in a ∼500 V/cm electric field. The pulse widths will be ∼10 ns, enabling it to operate in a flux of ∼6×10¹³ DT n/cm²/sec. A special collimator design is used, giving an estimated angular resolution of 4.5 degrees HWHM.