US 5,077,771 AGranted

Hand held high power pulsed precision x-ray source

AssigneeKevex X-Ray, Inc.

InventorsBrian Skillicorn, David C. Reynolds, Richard S. Burrow

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Abstract

A pulsed precision x-ray source includes a miniaturized internally self-shielding x-ray tube and an integral generator contained in a hand-held housing for generating timed bursts of x-ray having regulated energy level. A control grid and focus electrode within the tube enable precise on-off control of an electron beam directed to an x-ray emitting anode. The integral generator system includes an elongated, U-shaped unitary, molded plastic block mounted in the housing and includes a high voltage transformer having primary and secondary annular windings encased in a transformer portion of the block defining a central opening outside of the block for receiving a transformer core therethrough and, a capacitor-diode voltage multiplier stack connected to the secondary winding and having a positive node connectable to the anode and a negative node connectable to the cathode. A high voltage pulse width modulated switching circuit is connected to the primary annular winding to generate high voltages across said voltage multipler stack in order to control the energy of x-ray put out by the tube. A heater power supply supplies heater current to operate a heater in the tube. A focus element/grid control voltage power supply generates control voltages. A control circuit controls application of the control voltages to the focus element and the grid in order to switch the electron beam on and off in accordance with a preset value.

Claims41

Dependent claims

An integral high voltage generator for a ruggedized hand held precision x-ray source including an x-ray tube, the source being contained in a ruggedized hand-holdable housing and useful for generating bursts of x-ray photons having precisely regulated intensity level, energy level extending to at least 70 kilovolts, x-ray beam focus and burst duration, the x-ray tube having a heater, a heater power supply and an indirectly heated thermionic emission cathode electrode, a control grid, a focus electrode and a control grid and focus electrode power supply and an anode for emitting said bursts of x-ray photons as a consequence of bombardment of an accelerated electron beam pulse emitted by said cathode along a path leading to said anode, said integral generator including:

switching power supply means including an elongated, unitary, molded block mounted in the housing, the block having two generally parallel, externally cylindrical tube sections joined together along a rear portion of a central longitudinal axis;
high voltage transformer means having primary and secondary annular windings encased in a transformer portion of the block, said transformer portion having an inside periphery generally tangent to the central longitudinal axis thereof, and defining a central opening outside of the block for receiving transformer core means therethrough;
a two part capacitor-diode voltage multiplier stack having center nodes thereof connected to said secondary winding and having a positive node connectable to said anode and a negative node connectable to said cathode, a positive terminal providing part of said capacitor-diode voltage multiplier stack being formed in one of said cylindrical tube sections, and a negative terminal providing part of said capacitor-diode voltage multiplier stack being formed in another of said cylindrical tube section;
said one cylindrical tube section defining a well for receiving said x-ray tube therein in a manner by which said anode is thereupon electrically connected to a positive terminal of said positive terminal providing part.

1 more element

A pulsed precision x-ray source including an x-ray tube and integral generator system operable directly from a low voltage source and contained in a hand-holdable housing for generating timed intervals of x-ray photons having regulated intensity and energy level, and being emitted from an anode target area approaching a point source x-ray emitter;

the system comprising,
said x-ray tube having a heater and an indirectly heated thermionic emission cathode;
said anode target area emitting x-rays as a consequence of bombardment of an accelerated electron beam emitted by said cathode along a path leading to said anode;
a control grid disposed along said path through which said beam passes for controlling said beam, and a beam focus electrode for focusing said beam and directing it towards the target area of said anode,
said integral generator system including:
a unitary, molded plastic block structure mounted in the housing and including high voltage transformer means having primary and secondary annular windings encased in a transformer portion of the block and, a Cockcroft-Walton capacitor-diode voltage multiplier stack connected to said secondary winding and having a positive node connectable to said anode and a negative node connectable to ground,
high voltage pulse width modulated switching means connected to said primary annular winding for passing switching currents therethrough in order to generate controlled high voltages across said voltage multiplier stack in order to control the energy of x-ray photons put out by said x-ray tube,
heater power supply means for supplying regulated heater current to operate said x-ray tube heater at a regulated maximum temperature,
control voltage generation means for generating a grid control voltage for application to said control grid and for generating a focus voltage for application to said focus electrode,
grid control means connected for controlling application of said grid control voltage to said control grid of said x-ray tube in order to switch said beam on during a beam-on pulse time, said grid control means including timing circuit means for establishing the duration of the beam-on pulse time in accordance with a presettable value.

7 more elements

A precise x-ray pulse generating apparatus for generating an x-ray pulse of precise energy, intensity and duration, the apparatus including a housing and comprising:

shielded x-ray tube means in the housing including an evacuated envelope, electron gun means and a target disposed in facing relation in the envelope and an x-ray window for passing x-rays emitted from the target, the electron gun means for generating an electron beam pulse during beam-on precise intervals and for effectively inhibiting electron flow in the presence of high voltage fields during an operational interval other than a said beam-on interval therein, the electron gun means including an indirectly heated thermionic emission cathode electrode, a control grid and a focus electrode.
DC switching high voltage DC generator means for generating and applying one of a presettable plurality of kilovoltage potentials across the electron gun means and the target during the operational interval,
DC switching heater power supply means for generating and applying current to a heater for heating the cathode, the heater power supply means including regulation means for regulating the heater current to keep the heater from exceeding a maximum temperature,
DC switching control grid and focus electrode power supply means for generating and applying control voltages to the control grid and to the focus electrode,
beam interval control means including monitor means for monitoring the one kilovoltage potential applied across the electron gun and the target of the x-ray tube to ascertain that the said potential has substantially reached its preset value, presettable timer means responsive to the monitor means and to an external excitation signal for generating a control pulse having a preset duration, the control pulse for controlling the DC switching control grid and focus electrode power supply means for changing bias voltages applied to the control grid and to the focus electrode during the duration of the control pulse thereby to cause the said electron beam-on interval.

2 more elements

Dependencies are inferred from the claim text.