Single-shot microscopic electron imaging of intense femtosecond laser-produced plasmas

Abstract

A simple technique for single-shot microscopic electron imaging was demonstrated for the study of intense femtosecond laser-produced plasmas. Passed through a permanent magnet lens designed for 110-keV electrons, hot electrons emitted from the plasma produced by a single laser pulse of 0.8 mJ with intensity of 3 × 10(16) W/cm(2) were successfully imaged. Analyzing this image, we found that electrons were emitted from an area of 3 μm in diameter. At higher laser intensity of 10(18) W/cm(2), distinct structures were observed in and near the focal spot of the laser; that is, the electrons were emitted from several separate spots. These results show that laser-plasma electron imaging is promising for studying the interactions of femtosecond lasers with high-density plasmas.

Femtosecond electron deflectometry for measuring transient fields generated by laser-accelerated fast electrons

“…1, the electrons emitted in the target-normal (z-axis) direction could be collected, and the emission sources could be magnified and imaged with high spatial resolution by means of an electron imaging system that consisted of an electron lens and fluorescent screen. 21 The lens was set 17 mm behind the electron sources and had an aperture of 300 lm in diameter (solid angle 2.4 Â 10 À4 sr). The sensitivity of this electron imaging system is sufficiently high to obtain a distinct image in a single shot, and the energy of electrons imaged on the screen is selected by the lens; specifically, when the screen is placed 730 mm from the lens, the energy of imaged electrons is 120 keV.…”

Transient changes in electric fields induced by interaction of ultraintense laser pulses with insulator and metal foils: Sustainable fields spanning several millimeters

“…The probe pulses (laser-accelerated electrons) emitted in the target-normal direction (along the z axis) were collected, and images of the electron sources were obtained with a magnification ratio of 20 and high spatial resolution by using an electron imaging system composed of an electron lens, a fluorescent screen, and an electron-multiplying CCD camera [28], The energy of electrons reaching the screen was selected to be 120 keV using the electron lens. The distance L between the two laser spots was varied using the position control unit.…”

Highly intensified emission of laser-accelerated electrons from a foil target through an additional rear laser plasma

“…The zero delay time is determined to within AE500 fs through a cross-correlation measurement using two electron pulses [23]. The energy spectrum and beam profile of the electrons escaping from the rear side of the target to the vacuum are measured separately by a magnetic spectrometer and an electron imaging system [24], respectively. The electron imaging system is composed of an electron lens, a fluorescent screen, and an electron-multiplying charged coupled device (EM-CCD) camera.…”