Non-magnetic femtosecond electron source device with adjustable convergence angle

Abstract

The invention discloses a non-magnetic femtosecond electron source device with an adjustable convergence angle. The non-magnetic femtosecond electron source device comprises a vacuum cavity, and a photoelectric cathode, a grid electrode, an anode, an electric convergent mirror and an electric objective lens which are arranged in the vacuum cavity, have overlapped central axes and are sequentiallyarranged at intervals, the photoelectric cathode is used for generating femtosecond pulse electron beams under the excitation of femtosecond laser pulses; a voltage is applied between the photocathodeand the anode for accelerating the electron beam; the voltage of the electric convergent mirror and the voltage of the electric objective lens are adjustable, and the electric convergent mirror and the electric objective lens are used for converging the accelerated electron beams twice to obtain parallel beams or convergent beam electronic pulses with actually required convergence angles. According to the invention, the electric convergent mirror and the electric objective lens are adopted to focus the pulsed electron beam twice, and the voltage of the electric convergent mirror and the electric objective lens is flexible and adjustable, so that pulsed electron beams with different convergence degrees and beam spot sizes can be obtained. Moreover, the size of the electron source device can be greatly reduced by adopting the electrostatic lens, the structure is simple, and the quality, flexibility and controllability of the required electron beam can be further improved.

Description

technical field [0001] The invention belongs to the field of electron microscopic imaging, and more specifically relates to a non-magnetic femtosecond electron source device with adjustable convergence angle. Background technique [0002] Ultrafast electron diffraction, which is a combination of electron diffraction and ultrashort laser pulses, has become a new technology in the field of electron microscopy imaging. Ultrafast electron diffraction has the ability to resolve time and space at the scale of atomic motion, and can realize real-time observation of ultrafast dynamic processes in both time and space structures. It has a wide range of applications in research in the fields of chemistry, materials and biology. [0003] The key to ultrafast electron diffraction is to obtain high-quality ultrashort electron pulses, which determine the time and space resolution of this technology and the ability to obtain information about the dynamic process of the object under study. ...

AI Technical Summary

Problems solved by technology

[0006] The invention provides a non-magnetic femtosecond electron source device with adjustable convergence angle, which is used to solve the technical problem that the existing electron source device has a complex system due to the use of magnetic elements for focusing, which leads to difficulty in adjusting the convergence angle in practical applications

Images