title: Measurement of femtosecond electron pulse length and the temporal broadening due to space charge.
abstract: The temporal width of ultrashort electron pulses as a function of beam intensity was measured on the femtosecond time scale with a customized streak camera. The results show that the temporal profile of an electron pulse is Gaussian at low beam intensity and progressively evolves to a top-hat shape due to space charge broadening as the beam intensity increases. The strong correlation between the pulse width and beam intensity observed in our streaking measurements agrees very well with the mean-field calculation and supports the main conclusion of previous theoretical studies that the space charge broadening plays a determinant role.
authors.affiliation: Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.forename: Shouhua
authors.initials: S
authors.lastname: Nie
authors.forename: Hyuk
authors.initials: H
authors.lastname: Park
authors.forename: Junjie
authors.initials: J
authors.lastname: Li
authors.forename: Rick
authors.initials: R
authors.lastname: Clinite
authors.forename: Renkai
authors.initials: R
authors.lastname: Li
authors.forename: Xijie
authors.initials: X
authors.lastname: Wang
authors.forename: Jianming
authors.initials: J
authors.lastname: Cao