RMS Dynamic Simulation for Electron Cooling Using BETACOOL
RMS Dynamic Simulation for Electron Cooling Using BETACOOL. He Zhang Journal Club Talk, 04/01/2013. Outline. Basic idea of the RMS Dynamic Simulation Model of the ion beam Model of the electron beam Model of the cooler How BETACOOL performs the simulation
RMS Dynamic Simulation for Electron Cooling Using BETACOOL
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Presentation Transcript
RMS Dynamic Simulation for Electron Cooling Using BETACOOL He Zhang Journal Club Talk, 04/01/2013
Outline • Basic idea of the RMS Dynamic Simulation • Model of the ion beam • Model of the electron beam • Model of the cooler • How BETACOOL performs the simulation • A brief description of the simulation process • From emittances to coordinates to invariants • Friction force calculation • Transfer map of the cooler • Characteristic time/rate calculate • Emittance calculation He Zhang
Basic idea of the RMS Dynamic Simulation • Ion bunch has Gaussian distribution in all directions • Solve this equation: • In transverse direction, εiis the emittance in horizontal or vertical direction • In longitudinal direction, coasting beam; bunched beam; Ωsis the synchrotron frequency. He Zhang
Model of the ion beam • Two models: • Single particle model • Monte Carlo model • Parameters for ion beam: • Horizontal emittance • Vertical emittance • Momentum spread • Number of particles • Model particles (only for Monte Carlo model) He Zhang
Model of the electron beam • According to different geometry and different charge distribution, BETACOOL provides the following models: • Uniform cylinder, Gaussian cylinder, Hollow beam, Uniform bunch, Gaussian bunch, Electron array, Parabolic, File. • Set up the Gaussian bunch model One way: Input bunch size and angle, input number of electrons The other way: Input bunch size and choose from model, imputemittance, temperature, or r.m.s. velocity, input number of electrons. He Zhang
Model of the cooler • Parameters for the cooler: • Cooler length • Magnetic field • Section number • Bunch number • Distance between bunches • Cooler model: thin lens, Euler model, RungeKutta model • Integration steps (for Euler model and RungeKutta model) • Lattice: β, α, η, and ή • Shifts He Zhang
How BETACOOL performs the simulation He Zhang
Emittances to Coordinates to Invariants • Single particle model: Transversely, Longitudinally, He Zhang
Emittances to Coordinates to Invariants • Monte Carlo model Transversely, Longitudinally, Invariants are calculated statistically. He Zhang
Friction Force Calculation • Many friction force models: Consider Non-magnetic Meshkov model as an example Besides the constants, we need He Zhang
Friction Force Calculation • We have found • Many models for electron bunch distribution. Consider the Gaussian bunch as an example: Plug in the ion coordinates into the function above to get ne . • Define directly, or define temperature, emittance, velocity spread for the electron bunch, and the program will calculate • Now the friction force can be calculated. He Zhang
Calculate the New Emittance He Zhang
Thanks for your time! He Zhang