1. Warp simulations @ LBNL Warp suite of simulation codes: developed to study high current ion beams (heavy-ion driven inertial confinement fusion). High current beams necessary for a driver → the space-charge forces dominate over thermal forces (and magnetic self-fields at low velocity). → analysis of beam dynamics needs to include the electrostatic self-fields of the beam. Warp combines the PIC technique (uses the Lorentz equation of motion to advance in time macro-particles, which represent many real particles) with a description of the accelerator "lattice" of elements. The effects of the space-charge is included by a global solution of Poisson's equation, giving the electrostatic potential, at each timestep. Each time step goes through the following pattern: 1.) The charge of the macro-particles is deposited onto the mesh, using linear weighting. 2.) The charge density is calculated from the particles via triinear interpolation of the macro-particles onto the mesh. The electrostatic potential is calculated from the charge density by solving Poisson's equation. 3.) The electric fields are interpolated from the mesh to the macro-particles. 4.) The velocities and positions of the macro-particles are advanced. The macro-particles are advanced in time using a combination of the "leap frog" and "isochronous leap frog" methods.

2. Overview Purpose: Injection of laser-accelerated proton/electron beam and transportation through a collimating and debuching device. Already done: - Python input file modified for this different application - energydependent beam parameters included: spectrum, divergence, source size, transverse emittance (for protons and comoving electrons) - most diagnostics are included (1D, particles, potential, charge density) - emulation of experimental setup: same beam parameters, same dimension, same solenoid field (8.6 T) Current tasks and problems: - setting up more diagnostics (e.g. particle density, lost particles, RCF detector) - extended magnetic field - injection problems (λD, ωP) - optimization of simulation grid, timestep, particle number - electrons E>E comoving Future plans up to summer 2010: - Comparison of experimental data: collimating and focussing - Optimize next experiment - Different magnetic fields - Neutralizing background plasma - Debunching

3. Preliminary Results - 8.2e+12 protons & comoving electrons - 1e+6 simulation particles - 1e+4 plotted particles - timestep: 0.1 ps - grid fieldsolver: nr = 280, nz = 700, r: 0 – 14cm, z: -5 – 65cm Δr = 0.5 mm, Δz = 1 mm - B-Field: 8.6 T: 0 – 11.9cm (gray area no field) Observation: - B-Field collimation of electrons stronger than expansion due to space-charge forces - attraction of protons around beam axis