Patent Number: 039492320
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns nuclear oil well-logging in general. More specifically, it relates to an improvement applicable to a high-voltage neutron generator as used in a logging tool. It particularly deals with a detector for sensing and controlling arcing conditions. 2. Description of the Prior Art It has been found in connection with well-logging instruments of the type which use a neutron generator, that the exceedingly high voltage employed tends to create conditions such as to subject the generator to a high-voltage discharge, or breakdown. Furthermore, such conditions are unstable, and the arcs involved are frequent and large in amplitude. Consequently, if such arcs continue without control, the glass envelope of the neutron tube can be punctured. Clearly, such results are troublesome and expensive and may involve considerable loss of valuable equipment. Consequently, it is an object of this invention to provide a means for detecting arcing conditions so that protective steps may be taken to avoid destructive conditions. SUMMARY OF THE INVENTION Briefly, this invention concerns a high-voltage arc detector for protecting against breakdown of well-logging equipment where such equipment has a high-voltage supply and a neutron generator tube connected to said high-voltage supply. The invention comprises in combination a high-voltage connector for carrying said high voltage from said supply to said tube, and insulation surrounding said connector. It also comprises capacitance means associated with said connector for producing a signal when an arc occurs. Again, briefly, the invention concerns a high-voltage arc detector for protecting against breakdown of well-logging equipment, which has a high-voltage supply and a neutron generator tube connected to said voltage supply. It comprises in combination a cylindrical housing for said equipment enclosing said high-voltage supply and said neutron generator tube. It also comprises a section of said housing which encloses an axially located high-voltage connector comprising a metallic cylindrical conductor for carrying said high voltage from said supply to a target in said tube. It also comprises high-voltage insulation filling said housing section surrounding said cylindrical conductor, and a thin relatively narrow electrically conductive strip located in a circumferential groove in said insulation and located longitudinally between said high-voltage supply and said neutron generator tube, and radially spaced from said conductor in order to form an electrical capacitor therewith. It also comrpises a resistor connected between said strip and circuit ground, and an amplifier having an input and an output as well as a relay having a switch for controlling energization of said high-voltage supply. It also comprises first circuit means for connecting said strip to said amplifier input, and second circuit means for connecting said amplifier output to said relay in order to activate said relay whenever an arc occurs so that the high-voltage supply will be deenergized.