CST Validation for Beam Thermal Induced Effects Lorenzo Teofili (EN-STI-TCD) Impedance Meeting 03/11/2017 Many thanks Francesco Giordano for the help.
Scope of the Presentation • CST feat. ANSYS Results in the Impedance Induced Heating 3 D Map • The Method • A Real Application • Benchmark of the CST capabilities of computing Impedance Induced Heating • High Order Modes (HOMs) • Resistive Wall • Input Request
1. 1 The Method - Dissipated Power On the Walls FREQUENCY DOMAIN Such a formulation in very interesting because from it the Dissipated 3 D Power map can be easily obtained as:
1. 1 The Method - Dissipated Power On the Walls FREQUENCY DOMAIN CST is perfectly able to compute the surface currents on the geometry and to compute the associated thermal losses: 1 - add a Monitor “H Field and Surface Current” at the desired frequency 2 - Run the simulation 3 - Post Processing -> Thermal Losses -> Calculate (if needed modify the default value for the PEC conductivity)
1. 1 The Method - Dissipated Power On the Walls FREQUENCY DOMAIN After performing the previous indication In the Navigation Tree will appear a new item: “Thermal Losses” Opening it one can see the associated data, particularly the total power losses in the component, .
1. 1 The Method - Dissipated Power On the Walls FREQUENCY DOMAIN Once this is Done the problem has to be transformed in a thermal one, and the Power loss map can finally be imported and shown!
1. 2 CST feat. ANSYS – A Real Application The PSB absorber Scraper Beam The PSB scraper is a device installed in the PSB at CERN, aimed to clean the beam halo at the very early stage of acceleration. Two graphite blocks constitutes the scraping core of the device, and a Impedance induce Heating has been required in order to assess the necessity of an active cooling system.
1. 2 CST feat. ANSYS CST Dissipated Power Map Ansys Import
1. 2 CST feat. ANSYS – Ansys Temperature map for a thermal steady state analysis One last check, the total Power CST Computed Ansys Imported 0. 2 % OF ERROR IN THE IMPORT. 2% ERROR.
1. 2 CST feat. ANSYS Sum UP Thermomechani cal Simulations Perform the Electromagnetic Analysis Compute the Hsurface Current Field of the frequencies of Interest Import In ANSYS the “Corrected” Map For every Frequency of interest Compute the Thermal Losses for each frequency and obtain the Power Map
• Benchmark of the CST capabilities of computing Impedance Induced Heating • High Order Modes (HOMs) • Resistive Wall • Input Request
2. 1 HOMs - Dissipated Power In a Cavity L = 0. 6; % [m] length of the pillbox Rc = 0. 2; % [m] radius of the pillbox f = 0. 5714; % [GHz] frequency of the computed mode E 0 = 3. 335 e+6; % [V/m] Peak electric field CST Analytical Error 3. 56 e 4 2. 6721 e 6 W 2. 677 e+6 W 0. 2 % 3. 56 e 7 8. 4665 e 4 W 8. 449 e+4 W 0. 2 %
2. 1 HOMs - Dissipated Power In a Cavity Dissipated Power Map TM 010 L = 0. 6; % [m] length of the pillbox Rc = 0. 2; % [m] radius of the pillbox f = 0. 5714; % [GHz] frequency of the computed mode E 0 = 3. 335 e+6; % [V/m] Peak electric field CST Analytical Error 3. 56 e 4 2. 6721 e 6 W 2. 677 e+6 W 0. 2 % 3. 56 e 7 8. 4665 e 4 W 8. 449 e+4 W 0. 2 %
2. 2 Resistive Wall Impedance
2. 2 Resistive Wall Impedance ?
2. 2 Resistive Wall Impedance Expected Qualitative Behavior of the resistive wall impedance dissipated power with the frequency.
2. 2 Resistive Wall Impedance
3. INPUT REQUEST The Method seems Working, However: • Are there other simple analytical tests we can perform to be sure CST is giving the correct Dissipated Power Distribution? • Can we check the method “In Loco”, i. e. there is the possibility of considering an experimental set up and compare the CSTAnsys results with the real measurements?
Thank You For Your Attention
References  Uspas Slides pp. 10 -12 and pp. 52 http: //uspas. fnal. gov/materials/11 ODU/Proton_4. pdf  Power loss calculation in separated and common beam chambers of the LHC, C. Zannini, G. Rumolo, G. Iadarola, 5 th International Particle Accelerator Conference, Dresden, Germany, https: //cds. cern. ch/record/1742192/files/CERN-ACC-2014 -0122. pdf
Dissipated Power in a resistive wall Impedance Wakefield There are discrepancies between the power losses compute by CST and the one that came out from theory!!!!
Dissipated Power in a resistive wall Impedance Wakefield
Dissipated Power in a resistive wall Impedance Wakefield Wall Dissipated Power Beam Emitted Power The results are in a real GOOD AGREEMENT, THE MAXIMUM ERROR IS AROUND THE 3%. However, non physical over estimation of the wall dissipated power, if this is a general behavior of the software the it is not bad, CONSERVATIVE APPROACH.