Wakefield Calculations of DDS

Nate Folwell, Lixin Ge, Adam Guetz, Kwok Ko, Rich Lee, Zenghai Li, Cho Ng

Advanced Computations Department

Parallel EM Code Development at SLAC

 US DOE SciDAC Simulation Initiative supports the development of parallel electromagnetic codes formulated on unstructured grids to enable

Large-scale accelerator simulations

on DOE supercomputers

Generalized Yee Grid Finite-Element Discretization Tau3P/T3P Omega3P S3P Time Domain Simulation With Excitations Frequency Domain Mode Calculation Scattering Matrix Evaluation Track3P – Particle Tracking with Surface Physics

V3D – Visualization/Animation

of

Meshes, Particles & Fields  SciDAC collaborations are

maximizing code capability/performance

via advances in applied math, computer and computational science (e.g. new algorithms, refinement, partitioning, visualization, etc...)

DDS Wakefields in Time Domain

H60VG3 55-cell DDS w/ power and HOM couplers

Tau3P

simulation with beam

• 1 st wakefield analysis of an actual DDS prototype, • 1 st direct verification of DDS wakefield suppression by end-to-end simulation.

Transverse wakefield

DDS Wakefields in Frequency Domain

Omega3P/complex

solver is used to compute modes in 1 st and 3 rd dipole bands with HOM damping included:

1 st Band 3 rd Band

.

• Quadratic elements • 2.3 million DOFs • 94.5 million non-zeros • 3179 sec for 120 eigenpairs on 512 CPUs.

Mode with high Q that couples to the upstream damping manifold Mode with low Q that couples downstream to the HOM coupler

DDS Wakefields Comparison

Mode Spectrum Wakefields (V/pC/mm/m) in meters behind leading bunch

Omega3P Tau3P