(Wednesday, 8/1/2018) 1:45 PM - 3:45 PM
Room: Davidson Ballroom A
Purpose: From on-demand local production of PET isotopes to cell or small animal irradiation with heavy ions, an inexpensive, low energy ion accelerator can bring almost any centers clinical and/or research opportunities that are currently available only to the largest institutions. Our pulse line ion accelerator (PLIA) prototype is a simple coaxial accelerating structure capable of supporting the synchronous propagation of a high voltage (HV) pulsed electric field with the particles. Its simplicity makes the structure less expensive and potentially more robust than existing technologies.
Methods: Our prototype consists of an 8-gauge wire helix wrapped around a piece of 1.5� diameter quartz tube that provides proper vacuum for the ion propagation. That structure is coaxially nested inside a 4.5� conducting pipe. A bipolar pulse generator launches HV pulses up to 80kV onto the helix. The length of the prototype is 1.6m. Repetition rate and ion bunch charge parameters are designed to yield an ion beam charge of at least 10uC/s.
Results: The structure has been tested with 200ns pulses up to 20kV so far. @ 20kV, an accelerating gradient of 1.3MeV/m propagates at 1.610�m/s with only 10% of the amplitude being reflected at the end of the structure. A finite element model of the accelerator has been developed and agrees within 10% of measurements. The electric field strength is limited by arcing discharges inside the vacuum that are present at intermediate low pressures (10�¹-10³torr) but absent above and below. For regulatory and safety purposes, Dose equivalent estimates were obtained using transport calculations with MCMPX. For 1000 shots/day, the dose rate is <10uS/h @1m without shielding for protons up to 8MeV.
Conclusion: Simulations and PLIA measurements show that accelerating ions with a simple structure is possible. Current experimental gradients indicate that reaching 4MeV/m is realistic.
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