FNALMagnetronIonSource.PDF

FERMILAB-CONF-16-352-AD Overview of Recent Studies and Design Changes for the FNAL Magnetron Ion Source D.S. Bollinger1, a) and A. Sosa1, b) 1Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois, 605010 a)Corresponding author: bollinger@ b)asosa@ Abstract. This paper will cover several studies and design changes that will eventually be implemented to the Fermi National Accelerator Laboratory (FNAL) magnetron ion source. The topics include tungsten cathode insert, solenoid gas valves, current controlled arc pulser, cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor reduction. The studies were performed on the FNAL test stand described in [1], with the aim to improve source lifetime, stability, and reducing the amount of tuning needed. INTRODUCTION The FNAL magnetron ion sources provide ions for the neutrino program and other experiments. The typical run time in recent years has been at least 9 months long. As a result the ion sources need to provide stable beams for long periods of time. The studies and design changes discussed in this paper were performed to meet this goal. Issues such as hydrogen gas pressure and cesium boiler temperature greatly affect the stability of the source. And cathode erosion, which contributes to lifetime, is in part due to the duty factor seen by the ion source and the choice of cathode material. TUNGSTEN CATHODE INSERT One of the aging mechanisms of magnetron ion sources is cathode erosion. The erosion is caused by back