1. RF Modeling efforts on Ion Source at SNS Sung-Woo Lee

2. 2Managed by UT-Battelle for the U.S. Department of Energy Presentation_name 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

3. 3Managed by UT-Battelle for the U.S. Department of Energy Presentation_name EM (Electromagnetic) Model on SNS External Antenna Ion Source CST MWS model Antenna Lumped Input Port Plasma model (Lossy Metal) Antenna (Helical Coil) Magnet Holder (Copper) Housing (Stainless Steel)

4. 4Managed by UT-Battelle for the U.S. Department of Energy Presentation_name External Antenna Ion Source 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 Separator (Teflon) Ferrite Ring (  r : 250) Teflon/Ferrite/Teflon+Ferrite Cylinder  Ferrite :250  teflon :2.08) Magnet Holder (Copper) Antenna (Cu) Magnet Holder (Cu) Plasma Chamber

5. 5Managed by UT-Battelle for the U.S. Department of Energy Presentation_name E-H Field distribution E-field Case#2 Case#3 Case#4 H-field

6. 6Managed by UT-Battelle for the U.S. Department of Energy Presentation_name Surface Current Distribution Surface Current on the parts can be used for RF power loss estimation Case#2 Case#3 Case#4

7. 7Managed by UT-Battelle for the U.S. Department of Energy Presentation_name Power Dissipation Ratio on parts (%) Power losses calculated for each cases 2MHz Case #1Case #2Case #3Case #4 Teflon Cylinder w/o ferrite ring Teflon Cylinder w/ ferrite ring Ferrite Cylinder w/ ferrite ring Fer./Tef. Cylinder w/ ferrite ring Plasma Antenna39.62.938.72.253.41.238.62.2 Housing44.23.257.83.223.50.557.93.2 Magnet Holder15.11.12.00.15.40.12.10.1 Plasma92.794.597.894.5 Total Surface100.0 99.510083.199.699.5100 Total Volume0.0 0.50.016.90.40.50.0 Plasma no Plasma  Fer :250  tef :2.08) Teflon Cylinder Ferrite Cylinder Fer/Tef Cylinder Ferrite Ring

8. 8Managed by UT-Battelle for the U.S. Department of Energy Presentation_name Input Matching Performance Ferrite Cylinder Case #3 Teflon Cylinder Case #2 Fer/Tef Cylinder Case #4 No Ferrite Ring Case #1 2MHz 13MHz w/o Plasma w/ Plasma

9. 9Managed by UT-Battelle for the U.S. Department of Energy Presentation_name 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

10. 10Managed by UT-Battelle for the U.S. Department of Energy Presentation_name Surface Power Dissipation on Magnet Holder magnet holder power loss calculation based on F-domain solution for total loss… and t-domain solution for ratio between the surfaces… Case#1 no fer ring with tef cylinder Case#2 fer ring with tef cylinder Case#3 fer ring with fer cylinder Case#4 fer ring with fer/tef cylinder Total Surface Loss 100%1.595mW (1.498mW) 100%0.216mW (0.19mW) 100%0.408mW (0.325mW) 100%0.211mW (0.19mW) Face1 (toward antenna) 30% (30) 0.476mW (0.453mW) 8.2% (7.6) 0.018mW (0.014mW) 13.1% (13.5) 0.054mW (0.044mW) 19.7% (19.6) 0.042mW (0.037mW) Face2 (outer surface) 24% (23) 0.384mW (0.347mW) 23% (22.8) 0.049mW (0.043mW) 12.8% (12.8) 0.052mW (0.042mW) 15.1% (14.6) 0.032mW (0.028mW) Face3 (inner surface) 26% (26) 0.418mW (0.39mW) 22% (20.1) 0.047mW (0.038mW) 37.8% (36.3) 0.154mW (0.118mW) 42.6% (39.5) 0.09mW (0.075mW) Normalized with 1W input power Face 1 (Toward ANT) Face 2 (Outer) Face 3 (Inner)

11. 11Managed by UT-Battelle for the U.S. Department of Energy Presentation_name On going EM Modeling effort Complete drawing of external antenna (2MHz) Ion Source with secondary external antenna(13MHz) for plasma gun

12. 12Managed by UT-Battelle for the U.S. Department of Energy Presentation_name 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.