Computer modeling of a subfemtosecond photoelectron gun with time-dependent electric field for TRED experiments

Abstract

In the paper, theoretical and numerical studies on temporal focusing of photoelectron bunch in time-dependent fields are continued. Presented are the results of computer modeling on electron-optical system with combined time-dependent electric and static magnetic fields to ensure both spatial focusing and temporal compressing of photoelectron bunch down to sub-femtosecond level. The peculiarity of space charge effect contribution to the bunch broadening in the case of time-dependent electric field is discussed.

Hybrid dc–ac electron gun for fs-electron pulse generation

“…Slicing an ultrashort electron pulse out of a longer one by femtosecond electron pulse gating with surface plasmons [9] or by ponderomotive deflection [10] has also been proposed. Another suggestion is sub-fs pulse generation by electron bunching using a 'temporal lens' [11] or a cavity with a curve-shaped wall [12]. More recently, electron pulses emitted from a sharp tungsten tip by means of a few-cycle laser pulse have been observed and simulations indicate that single electron pulses of sub-fs duration may be generated in this way [13].…”

Double-mode electrostatic dispersing prism for electron pulse time-domain compression

“…More has been done theoretically and experimentally to obtain femtosecond or even attosecond electron pulse [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The techniques available now can be classified into two types.…”

“…For the first type the electron pulse duration is modulated with spatially nonhomogeneous stationary electromagnetic field provided by specifically devised electron-optical system [8,9,21,22], such as introducing the accelerating element in the traditional photoelectron gun [9]. In contrast to the first type, the electronpulse-duration modulation is accomplished by non-stationary electromagnetic field for the second one [10][11][12][13][14][15][16][17][18][19][20][23][24][25], in which electrons in different portion are subject to differential velocity (or energy) modulation. With these methods, progress has indeed been made theoretically on the time-resolved performance of UED.…”

Ultrashort pulse electron gun with a MHz repetition rate

“…With such a high acceleration field, generation of pulses with durations of less than 100 fs seems feasible. The additional possibility of temporal focusing by means of an electron energy chirp generated by an RF-cavity will allow advancing into the few-fs or even as-region [7][8][9][10].…”

“…Several methods have been used or proposed to generate ultrashort electron pulses in spite of space charge broadening. These include using a very short electron gun [2], applying relativistic electrons [6], and generating an energy chirp to focus temporally the electrons by means of a "temporal lens" [7] or by acceleration through an RF-cavity [8][9][10]. Yet another approach to eliminate space charge broadening is based on reducing the pulse charge to one or a few electrons per pulse.…”