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TY - UNPB AU - Todd, D.S. AU - Benitez, J.Y. AU - Lyneis, C.M. AU - Xie, D. ED - Schaa, Volker RW ED - Pisciotta, Pietro TI - Simulation and Experimental Studies of Biased Disc Behavior in the Superconducting ECR Ion Source VENUS J2 - Proc. of ECRIS2018, Catania, Italy, 10-14 September 2018 C1 - Catania, Italy T2 - International Workshop on ECR Ion Sources T3 - 23 LA - english AB - The use of a biased disc in place of a first stage injector in an ECR ion source was first reported at the 1990 ECRIS workshop. The improvements in both charge state distribution and beam current were significant: so much so that almost all ECR ion sources built since use biased discs instead of a first stage injector. Though now ubiquitous, exactly how a biased disc is affecting the plasma is not well-understood. The superconducting ECR ion source VENUS provides a good test bench for further studies of the biased disc as VENUS' flexibility allows for the production of moderate current, high current, and highly charged ion beams, and the biased disc operation can be vastly different for each of these operation modes. We present experimental results from varied biased disc operation with VENUS, and also for modifications to the biased disc such as decreasing its size and boring a hole in its center to inject additional electrons from a thermal cathode. Additionally, we have developed a code to investigate electron heating in VENUS. We will discuss results from these simulations which, when coupled with experimental results, will provide a better understanding of the biased disc. PB - JACoW Publishing CP - Geneva, Switzerland ER -