University of Oslo, Oslo, Norway
UCLA, Los Angeles, California, USA
SLAC, Menlo Park, California, USA
TUB, Beijing, People's Republic of China
MPI, Muenchen, Germany
We present the first results from experimental studies of the electron hose instability in the plasma-wakefield acceleration experiments at FACET. Theory and PIC simulations of an electron beam as it travels through a plasma indicate that hosing may lead to a significant distortion of the transverse phase space. The FACET dump line is equipped with a Cherenkov light based spectrometer which can resolve transverse motion as a function of beam energy. We compare the predictions from simulations and theory to the experimental results obtained.
SLAC, Menlo Park, California, USA
The Facility for Advanced Accelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 μm x 10 μm in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed.
SLAC, Menlo Park, California, USA
UCLA, Los Angeles, California, USA
When a positron beam enters a plasma, plasma electrons are drawn in toward the beam axis, creating a region of extremely large charge density with complicated, nonlinear fields. Few analytic solutions exist to describe these fields, and this necessitates the use of simulations to model positron beam and plasma interactions. This presentation should cover recent work on positron PWFA simulations using the QuickPIC* particle-in-cell code. I will discuss the computational challenges associated with positron PWFA and specific applications of the simulations for future experimental tests at the FACET user facility at SLAC.
* C. Huang et al., "QuickPIC: A highly efficient particle-in-cell code for modeling wakefield acceleration in plasmas," J. Comp. Phys. 217, 658 (2006).