Ultrafast High Voltage Kicker System Hardware for Ion Clearing Gaps

High current energy recovery linacs (ERLs), such as the one proposed for the JLab Electron Ion Collider cooling system, need temporal “gaps” to alleviate the ions trapped by strong Coulomb forces. Nearly rectangular pulses should kick the beam for ~100 ns at 10’s of MHz repetition rate and using very limited beamline space. These gaps must be imposed on a very low emittance, ultra-relativistic beam current of more than 100 mA. Such a high rep rate in combination with short interaction length leads to challenging requirements on the design of the very high voltage kicker and its driver operating at average power as high as 17 kW and with low parasitic impedances. RadiaBeam Systems will develop and ion clearing gap system integrating the following: i) About 4.2 kV deflector with ~14 mm interaction gap and ~0.5 m length shaped to minimize wakefield- induced emittance dilution; ii) 1.3968 MHz, 4.2 kV, 100 ns, <10 ns rise and fall times pulser using ultrafast GaN/SiC, Enhancement-mode, HV, field-effect transistors (FETs) connected in series and driven by a trigger with optical coupling; and iii) Cooling system using low-permittivity fluorocarbon liquid with mini-channeling effect in a finned structure formed by polycrystalline CVD diamond pads brazed to each other. In Phase I we will i) Develop a broadband stripline kicker with impedance-matched feedthroughs, terminating load and input port; ii) Develop a MHz-fast, nanosecond-front, HV pulser using advanced FETs and triggering immune to interferences; iii) Design cooing system for the HV FETs with parasitic capacitances as low as 1 pF to produce nearly rectangular waveforms; and iv) Develop experimental setup and mockup and perform measurements to demonstrate the feasibility of the approach. The target segment is nuclear physics accelerator labs, as well as free electron laser and advanced light source facilities. Other applications include civil and military electronic components including radars, power conversion devices, Pockels cells drivers for frontier lasers and high power electro-optics, ozonators, ground penetration radars, and pulsed radiolysis.