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RF Modeling efforts on Ion Source at SNS. Sung-Woo Lee. Outlines. External antenna Ion Source development at SNS Electromagnetic analysis Identifying the RF hotspots (E-H fields, Surface Current Distribution) RF power dissipation estimation on each parts
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RF Modeling efforts on Ion Source at SNS Sung-Woo Lee
Outlines • External antenna Ion Source development at SNS • Electromagnetic analysis • Identifying the RF hotspots (E-H fields, Surface Current Distribution) • RF power dissipation estimation on each parts • Input impedance estimation for input power matching • Modeling Challenges • Methods of analysis • Model Compatibility • On going EM modeling effort
EM (Electromagnetic) Model on SNS External Antenna Ion Source • CST MWS model Antenna (Helical Coil) Antenna Lumped Input Port Housing (Stainless Steel) Plasma model (Lossy Metal) Magnet Holder (Copper)
External Antenna Ion Source Teflon/Ferrite/Teflon+Ferrite Cylinder (mFerrite:250eteflon:2.08) • Power dissipation due to the RF input power needed to be estimated for complete thermal analysis on the sensitive part such as magnet holder. Antenna (Cu) Magnet Holder (Copper) Antenna Separator (Teflon) Ferrite Ring (mr: 250) Plasma Chamber Magnet Holder (Cu)
E-H Field distribution E-field H-field Case#2 Case#3 Case#4
Surface Current Distribution • Surface Current on the parts can be used for RF power loss estimation Case#3 Case#2 Case#4
Power Dissipation Ratio on parts (%) • Power losses calculated for each cases Teflon Cylinder Ferrite Cylinder Fer/Tef Cylinder no Plasma Ferrite Ring (mFer:250etef:2.08) Plasma
Input Matching Performance Teflon Cylinder Case #2 No Ferrite Ring Case #1 2MHz 13MHz w/o Plasma w/ Plasma Fer/Tef Cylinder Case #4 Ferrite Cylinder Case #3
RF EM modeling Challenges • EM analysis software tool (CST MWS, HFSS, etc.) • Analysis methods (CST MWS) • Transient solution (time-domain): • Hexahedron mesh (rectangular shape), Finite Difference Method (FDTD) • Frequency domain solution: • Tetrahedron mesh (arbitrary shape), Finite Element Method (FEM) DATA availability, Accuracy, Simulation Speed & Memory issues • Model Compatibility • Difficulties in drawing in 3-D EM modeling tool in some designs • Importing model created from mechanical CAD tool such as Solidworks
Surface Power Dissipation on Magnet Holder Face 2 (Outer) magnet holder power loss calculation based on F-domain solution for total loss… and t-domain solution for ratio between the surfaces… Face 3 (Inner) Face 1 (Toward ANT) Normalized with 1W input power
On going EM Modeling effort • Complete drawing of external antenna (2MHz) Ion Source with secondary external antenna(13MHz) for plasma gun
Summary • EM modeling on SNS External Antenna Ion Source for RF performance estimation. • RF E-H fields, Surface Currents, power losses are calculated. • Antenna input impedance for matching network design. • RF EM modeling issues in terms of simulation (speed, accuracy and data availability) and model compatibility are addressed. • Complete modeling for more close to real design is being developed.