COMPASS All-Hands Meeting,

1
Accelerator Prototyping Through Multi-physics
Analysis

• Volkan Akcelik, Lie-Quan Lee, Ernesto Prudencio,
• Cho Ng, Zenghai Li, Kwok Ko
• Advanced Computations Department
• Stanford Linear Accelerator Center

Work supported by DOE ASCR, BES HEP Divisions
under contract DE-AC02-76SF00515
2
Multi-physics Analysis for Accelerator Components

• Virtual prototyping through computing
• Thermal and mechanical analysis as important as
  EM analysis
• EM heating, Thermal radiation, Lorentz force
  detuning, Mechanical stress
• Augmented by additional physics
• particle effects including emittance and
  multipacting
• Nonlinear and transit effects in superconducting
  cavity design
• Accurate and reliable multi-physics simulation
  requires large-scale parallel computing TEM3P

3
TEM3P Multi-Physics Analysis

• Finite element based with higher-order basis
  functions
• Natural choice FEM originated from structural
  analysis!
• Use the same software infrastructure as Omega3P
• Reuse solvers framework
• Mesh data structures and format
• Parallel

CAD Model
EM Analysis
Thermal Analysis
Mechanical Analysis
4
TEM3P for LCLS RF Gun
CAD Model (courtesy of Eric Jongewaard)
Benchmark TEM3P against ANSYS
Thermal/Mechanical Domain
EM Domain
5
RF Gun EM analysis
1st mode 2.8411 GHz

• The second mode is operating mode
• Its magnetic field on the cavity inner surface
  generates heating!

2nd mode 2.8561 GHz
6
Mesh for Thermal/Mechanical analysis
Mesh 0.6 million nodes. Materials Copper
Stainless steel Thermal analysis 7 cooling
channels
EM Heating
7
Parameters for Thermal Analysis

• TEM3P cooling channels modelled as Robin BC
• 7 cooling channels
• specific temperatures and film coefficients
• Thermal load from EM power loss (4000 Watt)
• EM Heating BC
• Thermal conductivity for copper 391
• Thermal conductivity for stainless steel 16.2
• Other surfaces modelled as homogeneous Neumann BC

8
Thermal Analysis loaded with EM Heating
Temperature Distribution
TEM3P
ANSYS
Maximal Temperature 49.82 C
Maximal Temperature 49.96 C
9
Mechanical Analysis with Thermal Load
ANSYS
TEM3P
Maximal displacement 37.10 ?m
Maximal displacement 36.99 ?m

• Future work compute stress and shifted frequency
  due to geometry change

10
Multi-physics Analysis for SRF Cavities and
Cryomodules

• Thermal behaviors near superconducting region are
  highly nonlinear
• SRF Cavity wall is very thin
• Anisotropic high-order mesh will reduce
  significant amount of computing
• Working with RPI/ITAPS