We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium (Ca + ) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and Ca + are co-trapped, the reaction rate is measured by continuously quenching the reaction product Na + from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reactionrates between Na[S or P] and Ca + [S or D] at different collision energies. With the exception of the largest reaction-rate channel (Na[S] + Ca + [D]), our rates agree with classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance-channels.
In this work, we report the use of commercial gallium nitride (GaN) power electronics to precisely switch complex distributed loads, such as electron lenses and deflectors. This was accomplished by taking advantage of the small form-factor, low-power dissipation, and high temperature compatibility of GaN field effect transistors (GaNFETs) to integrate pulsers directly into the loads to be switched, even under vacuum. This integration reduces parasitics to allow for faster switching and removes the requirement to impedance match the load to a transmission line by allowing for a lumped element approximation of the load even with subnanosecond switching. Depending on the chosen GaNFET and driver, these GaN pulsers are capable of generating pulses ranging from 100 to 650 V and 5 to 60 A in 0.25–8 ns using simple designs with easy control, few-nanosecond propagation delays, and MHz repetition rates. We experimentally demonstrate a simple 250 ps, 100 V pulser measured by using a directly coupled 2 GHz oscilloscope. By introducing resistive dampening, we can eliminate ringing to allow for precise 100 V transitions that complete a −10 to −90 V transition in 1.5 ns, limited primarily by the inductance of the oscilloscope measurement path. The performance of the pulser attached to various load structures is simulated, demonstrating the possibility of even faster switching of internal fields in these loads. We test these circuits under vacuum and up to 120 °C to demonstrate their flexibility. We expect these GaN pulsers to have broad application in fields such as optics, nuclear sciences, charged particle optics, and atomic physics that require nanosecond, high-voltage transitions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.