Electron beam dynamics Christelle Bruni LAL

Activities Linear accelerator Rings Effect of the CSR and the laser shape on the compression (CSRtrack, Astra) Beam Break Up estimation for ERL(BI) Photoinjector caracterisation on PHIL (experiment, ASTRA) Alternative ERL design for THOMX (Astra, beta) Rings Longitudinal dynamics (2D tracking home code) Super-ACO (includinf FEL effect), ATF, ThomX (including CBS recoil effect) FELs (models, feedback, non linear dynamics) 50 MeV ring optics design on ThomX (beta code) Vaccum effects : multiple scattering, ion instabilities Intrabeam scattering (Mtingwa model) X-ray brilliance and flux evaluation (CAIN)

ARC-EN-CIEL accelerator design

Emittance degradation in the chicane

Longitudinal phase space degradation Space charge force non linearities Non uniformity induced by the CSR

Ellipsoid shape of the laser can

Improvement of the longitudinal phase space Compression To improve the longitudinal phase space Harmonic cavity Lenghen the laser as possible To improve emittance Laser pulse shape Optical function

PHIL : photoinjector beam test line

PHIL with AlphaX gun

Laser on the virtual cathode Charge measurement Laser on the virtual cathode

Charge simulation Including Aperture of the beam line Schottcky effect

Transverse size characterization Experiment for different gradient Simulations including the non linearity of the solenoid field

Project on short bunches fs laser Ultimate electron beam performances 100 pC, 150 fs THz modulation To obtain fs bunch train ps modulated laser based on a Michelson interferometer as in the experiment on the Japanese synchrotron UVSOR (S. Bielawski and C. Szwaj from Lille) : “chirped pulse beating” Funding request to the ANR french agency

Difficulties due to short bunches Preserve duration during transport Avoid bunch lengthening due to different path length during focusing Take care of the transverse pointing stability for capillary injection (tolerance less than 10 µm) Evaluation of the emittance degradation due to multiple scattering in gas before the capillary ? If shortest bunches needed, is the magnetic chicane envisaged to be added at highest energy ? Laser fs at the photocathode ? Laser shaping existing ? If not required ?