OPTICALLY DRIVEN AND CONTROLLED X-RAY SOURCE

THERE IS NEED FOR CONVENIENT, VERSATILE X-RAY SOURCES WHICH CAN BE PRECISELY CONTROLLED SPATIALLY AND TEMPORALLY. USED STROBOSCOPICALLY, SUCH DEVICES COULD REVOLUTIONIZE NON-DESTRUCTIVE TESTING AND BE UTILIZED WITH ADVANTAGE IN MORE CONVENTIONAL ROLES, INCLUDING MEDICAL DIAGNOSTICS AND HIGH SENSITIVITY DETECTION. A CANDIDATE, THE OPTICALLY DRIVEN AND CONTROLLED X-RAY SOURCE (ODX), HAS BEEN DEMONSTRATED AT THE LAWRENCE LIVERMORE NATIONAL LABORATORY. IT COMPRISES A TRANSMISSION PHOTOCATHODE IN CLOSE PROXIMITY TO A METAL-COATED TRANSMISSION ANODE. THE FIELD ACROSS THE VACUUM GAP BETWEENTHE ELECTRODES IS SUFFICIENTLY HIGH TO PRODUCE A PROXIMITY FOCUSSED REPLICA OF THE PHOTOCATHODE EMISSION AT THE ANODE. THIS IS A SOURCE OF CHARACTERISTIC X-RADIATION WITH SPACE AND TIME CHARACTERISTICS OF THE OPTICAL BEAM ILLUMINATING THE PHOTOCATHODE. PXL PROPOSES TO PRODUCE A LOW COST ODX WHICH IS FAR MORE ROBUST THAN THESE EARLIER PROTOTYPES AND CAPABLE OF HIGH FREQUENCY OPERATION. PHASE I WILL STUDY THE SUITABILITY OF, AND MEANS OF IMPLEMENTING, GAAS NEGATIVE ELECTRON AFFINITY PHOTOCATHODES IN THE ODX, AND DESIGN: -NEW ELECTRODES CAPABLE OF OPERATING AT 30 KV. -SECTORED ANODES FOR CHARACTERISTIC X-RAY SELECTION. -INEXPENSIVE METHODS FOR MOUNTING ANODE WINDOWS. PHASE II WILL FOCUS ON EVALUATING PHOTOCATHODE OPTIONS FOR MINIMUM COST AND COMPLEXITY, MAXIMIZING PERFORMANCE.