Abstract: A method for operating a pulsed neutron generator including an ionizer with an electron emitting cathode and a grid wherein the cathode and grid are disposed in a sealed chamber. At least one of the following is applicable to the ionizer; a distance between the cathode and the grid, a cathode current and/or a potential on the grid are selected such that the ionizer operates at most about one-half the space charge limited current for a grid current selected to provide a predetermined amount of neutron production.

Abstract: A well logging instrument includes an instrument housing to traverse a wellbore penetrating subsurface formations. An electrically operated energy source that emits ionizing radiation is disposed inside the housing. An insulating sleeve is disposed between the energy source and an interior wall of the housing. The insulating sleeve comprises a thin dielectric film arranged in a plurality of tightly fitting layers of dielectric material disposed adjacent to each other and successively. A thickness of each layer and a number of layers is selected to provide a dielectric strength sufficient to electrically insulate the energy source from the housing and to provide a selected resistance to dielectric failure resulting from the ionizing radiation.

Abstract: A well logging instrument includes an instrument housing to traverse a wellbore penetrating subsurface formations. An electrically operated energy source that emits ionizing radiation is disposed inside the housing. An insulating sleeve is disposed between the energy source and an interior wall of the housing. The insulating sleeve comprises a thin dielectric film arranged in a plurality of tightly fitting layers of dielectric material disposed adjacent to each other and successively. A thickness of each layer and a number of layers is selected to provide a dielectric strength sufficient to electrically insulate the energy source from the housing and to provide a selected resistance to dielectric failure resulting from the ionizing radiation.

Abstract: A VCSEL is provided that integrates an absorbing layer sandwiched within a null of the standing wave in the emitting mirror to reduce the reflectivity and transmissivity of the emitting mirror as seen by the feedback optical wave, with minimal effect on the reflectivity of the emitting mirror as seen by the light exiting the cavity. The absorbing layer may be made of a suitable absorbing material, such as a GaAs layer in a laser emitting near 850 nm or highly doped p-layer, for instance, and may be disposed epitaxially in a semiconductor or metamorphic mirror. The absorbing layer sandwich may be incorporated into the VCSEL after the last mirror pair or at any desired position with the emitting mirror array.

Abstract: A VCSEL is provided that integrates an absorbing layer sandwiched within a null of the standing wave in the emitting mirror to reduce the reflectivity and transmissivity of the emitting mirror as seen by the feedback optical wave, with minimal effect on the reflectivity of the emitting mirror as seen by the light exiting the cavity. The absorbing layer may be made of a suitable absorbing material, such as a GaAs layer in a laser emitting near 850 nm or highly doped p-layer, for instance, and may be disposed epitaxially in a semiconductor or metamorphic mirror. The absorbing layer sandwich may be incorporated into the VCSEL after the last mirror pair or at any desired position with the emitting mirror array.