  The Long Baseline Neutrino Facility (LBNF) will produce the worlds most
intense neutrino beam. Three series connected magnetic horns will require 5kV,
300kA, 800$\mu$s pulses at a rate of 0.7Hz to focus the beam. Fermilab has
designed and built pulsed high current supplies for horns in the past. Pulsed
currents of 205 kA for Neutrinos at Main Injector (NuMI - NOvA), focusing a 120
GeV beam, and 170 kA for Booster Neutrino Beam (BNB - MiniBooNE) for focusing
an 8 GeV beam have been operational for about 18 years. While the magnetic
horns are expected to be replaced, the LBNF horn power supply is expected to
last the lifetime of the project, 30 years. A resonant, half sine wave pulser
was used for NuMI and BNB and has many practical advantages. The system has
impedance limited fault currents by design, albeit large ones. That along with
the resonant behavior means that thyristor switches are well suited. Many fault
modes of the system have also been calculated. Several circuit changes were
incorporated so that a single fault can be tolerated. The supply must be
reversable to enable both neutrinos and anti-neutrinos to be produced. These
reversal requirements required a significant amount of mechanical design and
consideration to allow for quick reversal of all the semiconductors.
