ANSAT - AN ANTENNA SHEATH ANALYSIS TOOL

THE GOAL OF THE PHASE I RESEARCH IS TO DEVELOP A PRELIMINARY VERSION OF ANTENNA SHEATH ANALYSIS TOOL (ANSAT), A POST-PROCESSOR FOR THE ARGUS CODE. ARGUS IS AN EXISTING FULL WAVE ELECTROMAGNETIC CODE WHICH CAN BE USED TO DETERMINE THE ELECTROMAGNETIC FIELDS PRODUCED BY ICRF (ION CYCLOTRON RANGE OF FREQUENCIES) ANTENNAS IN THE CONTEXT OF ION-CYCLOTRON HEATING OF FUSION PLASMAS. THE ANSAT CODE WILL USE THE OUTPUT FROM ARGUS TO CALCULATE RADIO FREQUENCY (RF)-SHEATH DRIVING VOLTAGES ON THE FARADAY SHIELD OF AN ANTENNA. IN PHASE I, CRITICAL ASPECTS OF THE PHYSICS AND CODE DEVELOPMENT WILL BE EXAMINED IN ORDER TO ASSESS THE PROSPECTS FOR DEVELOPING A COMPLETE SHEATH ANALYSIS TOOL IN PHASE II. A PRELIMINARY VERSION OF THE CODE WILL BE DEVELOPED IN PHASE I TO SHOW HOW THE RF SHEATHS DRIVING VOLTAGES CAN BE CALCULATED AND EMPLOYED TO ASSESS THE STRENGTHS AND WEAKNESSES OF AN ANTENNA DESIGN WITH RESPECT TO CRITICAL VOLTAGE HANDLING AND EDGE PLASMA INTERACTION ISSUES. THESE ISSUES INCLUDE HOT SPOTS ON THE SCREEN, WEAK POINTS WITH REGARD TO BREAKDOWN, ICRF-CONVECTIVE CELLS, POWER DISSIPATED IN THE SHEATHS, AND THE INFLUX OF IMPURITIES RESULTING FROM RF-DRIVEN SPUTTERING PROCESSES AT THE FARADAY SHIELD.