GB1190991A - Improvements relating to Neutron Generation - Google Patents

Abstract

1,190,991. Ion beam tubes. KAMAN CORP. 16 May, 1967, No. 22609/67. Heading H1D. [Also in Division G3] Neutron generating apparatus comprises a sealed envelope containing an ion source 12 and axially spaced earthed target 28 adapted to include a substance (e.g. deuterium or tritum) which reacts with impinging ions to produce neutrons, loaded reservoir 76 for releasing a hydrogen isotope within the chamber and an A.C. source connected between the ion source and the target. Accelerator tube 10 and the power supply (11), (Fig. 5, not shown) may be mounted within a protective housing containing oil or gas under pressure or evacuated to protect components from voltage breakdown. Cathodes 82 and 58 are preferably magnetic, and anode 88 within magnet 96 is preferably non-magnetic. Electrode 68 facing control electrode 62, defocuses the ion beam over the target and suppresses secondary emission which latter may also be achieved by a wire electrode (140), (Fig. 2, not shown). Reservoirs 76, 78 and 80 of Zr or Ti are respectively loaded with tritium, deuterium and unloaded reservoir 80 gettering non-reactive gases. Tritium loaded Ti or Zr target 28 may be on a Cu backing. Ion source pressures may be 10<SP>-4</SP> to 10<SP>-3</SP> mms. Hg and deuterium and tritium gas pressures of 2 Î 10<SP>-9</SP> to 1 Î 10<SP>-3</SP> mms. Hg are instanced. A control system for adjusting the pressure during tube operation includes a motor (130), (Fig. 5, not shown), controlling the reservoir (78) currnet through a rheostat (132), the forward or reverse windings (126 and 128) of the motor being selectively activated from the transistor amplifier (116). The amplifier input signal is from lead (108) of the A.C. transformer supply and is proportional to the target current. In a construction wherein electrode 68a is earthed, and a wire anode 140 is provided in series with large resistor 146, the pressure may be measured during the negative half cycles of operation (Fig. 2, not shown). The target may be preloaded or loaded and replenished in situ. The initial degassing process includes heating to 415‹ C. until a pressure of 1 Î 10<SP>-7</SP> mm. Hg is reached. In operation, to load or replenish the target, relatively low voltages (e.g. 20 to 75 kv) are applied between target and source while one of deuterium or tritium is present, this gas then being replaced by the alternative prior to high voltage application (e.g. 100 to 170 kv) between target and source for neutron generation. Focusing and gating electrode (148) and a PIG pressure gauge (158) may be included (Fig. 3, not shown). Applications to oil well logging and neutron reactor tests are instanced.