Improvement of electron beam quality in optical injection schemesusing negative plasma density gradients

Journal Article · Tue Jul 26 04:00:00 EDT 2005 · Physical Review E

OSTI ID:878708

Fubiani, G; Esarey, E; Schroeder, C B; Leemans, W P

Enhanced electron trapping using plasma density down ramps as a method for improving the performance of laser injection schemes is proposed and analyzed. A decrease in density implies an increase in plasma wavelength, which can shift a relativistic electron from the defocusing to the focusing region of the accelerating wakefield, and a decrease in wake phase velocity, which lowers the trapping threshold. The specific method of two-pulse colliding pulse injector was examined using a three-dimensional test particle tracking code. A density down-ramp with a change of density on the order of tens of percent over distances greater than the plasma wavelength led to an enhancement of charge by two orders in magnitude or more, up to the limits imposed by beam loading. The accelerated bunches are ultrashort (fraction of the plasma wavelength, e.g., {approx}5 fs), high charge (>20 pC at modest injection laser intensity 10{sup 17} W/cm{sup 2}), with a relative energy spread of a few percent at a mean energy of {approx}25 MeV, and a normalized root-mean square emittance on the order 0.5 mm mrad.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director. Office of Science. Office of High EnergyPhysics
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 878708
• Report Number(s): LBNL--58354; BnR: KA1501020
• Journal Information: Physical Review E, Journal Name: Physical Review E Journal Issue: 2pt2 Vol. 73
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ELECTRON BEAMS
ELECTRONS
FOCUSING
LASERS
PERFORMANCE
PHASE VELOCITY
PLASMA
PLASMA DENSITY
TEST PARTICLES
TRAPPING
WAVELENGTHS
plasma density laser wakefield accelerator