AURORA RISE TIME SHARPENING WITH INDUCTIVE EROSION IN PRE-IONIZED PLASMA CHANNEL

A RESEARCH PROGRAM TO ANALYZE AND TO DEMONSTRATE THE FEASIBILITY OF A NEW TECHNIQUE TO SHARPEN THE BEAM PULSE RISE TIME OF THE AURORA FLASH GAMMA RAY SIMULATOR IS PROPOSED. THIS TECHNIQUE EMPLOYS THE INDUCTIVE EROSION PHENOMENA TO ERODE THE CURRENT RISE TIME OF THE AURORA BEAM PULSE, BY PROPAGATING IT THROUGH A PRE-IONIZED PLASMA CHANNEL ALONG THE AXIS OF THE EXISTING AURORA DRIFT TUBE. INDUCTIVE EROSION IS AN EXPERIMENTALLY VERIFIED PHYSICAL MECHANISM IN WHICH THE BEAM FRONT, IN EXPELLING THE CHANNEL ELECTRONS TO ESTABLISH CHARGE NEUTRAILITY, CONTINUALLY LOSES KINETIC ENERGY AND ERODES AWAY. SINCE THE CHARACTERISTIC TIME SCALE IS THE ACTUAL TIME TO EXPEL THE CHANNEL ELECTRONS TO THE DRIFT TUBE WALL, IT IS EXPECTED THAT THE RESULTING FINAL BEAM RISE TIME WILL BE ABOUT 2 NANOSECONDS. IN FACT, SUBSTANTIAL RISE TIME REDUCTIONS DUE TO THIS MECHANISM HAVE BEEN CONCLUSIVELY OBSERVED IN MODERATE CURRENT ( KA) PRE-IONIZED CHANNEL EXPERIMENTS. FURTHER, THIS MECHANISM IS ALSO SUSPECTED TO BE THE DOMINANT EROSION MECHANISM IN THE RECENT AURORA LOW PRESSURE NEUTRAL GAS CELL TECHNIQUE IN WHICH THE CHARACTERISTIC TIME SCALE IS THE CHANNEL ELECTRON EXPULSION TIME PLUS THE BEAM-INDUCED IONIZATION TIME ( NS). THUS, BY PREFORMING THE PLASMA CHANNEL, SUBSTANTIAL RISE TIME ENHANCEMENT CAN BE ACHIEVED IN ABOUT 3 METERS OF PROPAGATION, ACCORDING TO PRELIMINARY CALCULATIONS. THE OBJECTIVES OF THE PHASE I PROGRAM ARE TO PERFORM AN AURORA FEASIBILITY STUDY, TO IDENTIFY CRITICAL HARDWARE COMPONENTS FOR A SCALED EXPERIMENT ON AN ALTERNATIVE HDL FACILITY (E.G., TEMPO) THAT CAN BE PERFORMED IN THE EARLY PART OF PHASE II, AND TO ESTABLISH EXPERIMENTAL PARAMETERS FOR A PRELIMINARY HARDWARE DESIGN THAT COULD BE TESTED ON AURORA IN THE LATER PART OF PHASE II PROGRAM.