Fig. 2. Energy modulation and standing-wave terahertz interaction.

(A) Energy spectrum of electron pulses after interaction with the compression waveguide as a function of terahertz delay. (B) Measured energy modulation (black) by electric fields in comparison to the measured transversal deflection by magnetic fields (green). Shaded area indicates standard deviation of the deflection data. Time I is ideal for pulse compression, time II produces tilted pulses, and time III is ideal for stretching electron pulses in time. (C) Measured (left) and simulated (right) central energy modulation of compressed electrons (I) as a function of position x and y across the beam. (D) Measured (left) and simulated (right) central energy modulation of the electron beam at an improper interaction time (II). a.u., arbitrary units.