Abstract: A method for downhole generation of non-radioactive neutron radiation arranged so as to be able to generate reverberation, particularly gamma radiation, from the surroundings of a borehole, the method comprising the steps of: exciting laser light in a multistage laser light booster by means of a pump-type laser light source so as to form a pulsed laser light, the incoming light energy being concentrated in restricted laser light pulses representing a higher amount of light energy than that of the continuous flux of laser light; forming a drop of a neutron-enriched fluid within a space in a vacuum chamber; focusing the pulsed secondary laser light rays, which are directed toward the drop from substantially diametrically opposite directions, at a point in the drop, the drop consequently being compressed and heated so as to cause the neutron-enriched fluid in the drop to emit neutron radiation to the surroundings, thereby forming a high-energy reverberation, at least in the gamma frequency range, from the surrou

Abstract: A high voltage supply is provided for a neutron tube used in well logging. The "biased pulse" supply of the invention combines DC and "full pulse" techniques and produces a target voltage comprising a substantial negative DC bias component on which is superimposed a pulse whose negative peak provides the desired negative voltage level for the neutron tube. The target voltage is preferably generated using voltage doubling techniques and employing a voltage source which generates bipolar pulse pairs having an amplitude corresponding to the DC bias level.

Abstract: A neutron accelerator tube having a replenisher section for supplying accelerator gas, in ionization section adjacent the replenisher section adapted to receive the accelerator gas, and a target section adjacent the ionization section. The target section includes a chamber having a tritium target therein. A cathode member is interposed between the ionization section and the target chamber and has a recessed convergent surface exposed to the target chamber. An aperture in the cathode member at the vortex of this recessed surface provides for the extraction of ionized accelerator gas from the ionization section into the target chamber. An extraction electrode is also located in the target chamber between the target and the cathode and has a divergent projecting surface facing the recessed cathode surface. This electrode has an aperture at the apex of the projecting surface through which ionized accelerator gas may may be directed at the target.