Publication Date:
2018-03-29
Description:
Publication date: May 2018 Source: Ultramicroscopy, Volume 188 Author(s): W. Verhoeven, J.F.M. van Rens, E.R. Kieft, P.H.A. Mutsaers, O.J. Luiten Ultrashort, low-emittance electron pulses can be created at a high repetition rate by using a TM 110 deflection cavity to sweep a continuous beam across an aperture. These pulses can be used for time-resolved electron microscopy with atomic spatial and temporal resolution at relatively large average currents. In order to demonstrate this, a cavity has been inserted in a transmission electron microscope, and picosecond pulses have been created. No significant increase of either emittance or energy spread has been measured for these pulses. At a peak current of 814 ± 2 pA, the root-mean-square transverse normalized emittance of the electron pulses is ɛ n , x = ( 2.7 ± 0.1 ) · 10 − 12 m rad in the direction parallel to the streak of the cavity, and ɛ n , y = ( 2.5 ± 0.1 ) · 10 − 12 m rad in the perpendicular direction for pulses with a pulse length of 1.1–1.3 ps. Under the same conditions, the emittance of the continuous beam is ɛ n , x = ɛ n , y = ( 2.5 ± 0.1 ) · 10 − 12 m rad. Furthermore, for both the pulsed and the continuous beam a full width at half maximum energy spread of 0.95 ± 0.05 eV has been measured.
Print ISSN:
0304-3991
Topics:
Electrical Engineering, Measurement and Control Technology
,
Natural Sciences in General
,
Physics
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