Tecnai module

The Tecnai module can be used to turn a Tecnai transmission electron microscope into an ultrafast electron microscope. This is done by streaking the DC electron beam across a slit using a deflection cavity operated in TM110 mode. The deflection cavity is a compact, single-cell, power-efficient resonant microwave cavity, supporting a TM110 mode at a resonance frequency of 2.9985 GHz and a second mode which is orthogonal to the first mode oscillating at a frequency of 3.0735 GHz (difference 75 MHz). Both modes have an unloaded quality factor that can be as high as Q ≈ 5000. The deflection cavity is a pillbox cavity partially filled with a dielectric material with a large permittivity ε and a small tan δ, which allows a substantial reduction in size and power consumption. The TM110 mode has an oscillating magnetic field oriented perpendicular to the symmetry axis, allowing periodic deflection of the electron beam passing through. Due to the second mode the beam is deflected in both directions perpendicular to the propagation axis resulting in a Lissajous-like streak pattern (right picture). Presently the ceramic ZrTiO4 is used, with ε ≈ 36 and tan δ ≈ 0.0002 at 3 GHz, enabling an on-axis magnetic field amplitude of 3 mT at an RF input power of 15 W. Additionally the dielectric can be coated to prevent charging due to the electron beam passing through. Operating at full power the module can deliver 100 fs electron pulses while maintaining the electron beam quality. This can either be done at a repetition rate of 3 GHz or 75 MHz depending on single or dual mode operation, respectively. If interested pleas contact us to discuss the possibilities.

Ultrafast electron microscopy

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