  IsoDAR is a novel experiment designed to measure neutrino oscillations
through $\bar{\nu}_e$ disappearance, thus providing a definitive search for
sterile neutrinos. In order to generate the necessary anti-neutrino flux, a
high intensity primary proton beam is needed. In IsoDAR, $\mathrm{H}_2^+$ is
accelerated and is stripped into protons just before the target, to overcome
space charge issues at injection. As part of the design, we have refined an old
proposal to use an RFQ to axially inject bunched $\mathrm{H}_2^+$ ions into the
driver cyclotron. This method has several advantages over a classical low
energy beam transport (LEBT) design: (1) The bunching efficiency is higher than
for the previously considered two-gap buncher and thus the overall injection
efficiency is higher. This relaxes the constraints on the $\mathrm{H}_2^+$
current required from the ion source. (2) The overall length of the LEBT can be
reduced. (3) The RFQ can also accelerate the ions. This enables the ion source
platform high voltage to be reduced from 70 kV to 15 kV, making underground
installation easier. We are presenting the preliminary RFQ design parameters
and first beam dynamics simulations from the ion source to the spiral inflector
entrance.
