Daoud Hazem, Floettmann Klaus, Dwayne Miller R J
Departments of and Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
DESY, Notkestrasse 85, 22603 Hamburg, Germany.
Struct Dyn. 2017 Apr 12;4(4):044016. doi: 10.1063/1.4979970. eCollection 2017 Jul.
We present an RF gun design for single shot ultrafast electron diffraction experiments that can produce sub-100 fs high-charge electron bunches in the 130 keV energy range. Our simulations show that our proposed half-cell RF cavity is capable of producing 137 keV, 27 fs rms (60 fs FWHM), 10 electron bunches with an rms spot size of 276 m and a transverse coherence length of 2.0 nm. The required operation power is 9.2 kW, significantly lower than conventional rf cavity designs and a key design feature. This electron source further relies on high electric field gradients at the cathode to simultaneously accelerate and compress the electron bunch to open up new space-time resolution domains for atomically resolved dynamics.
我们展示了一种用于单次超快电子衍射实验的射频枪设计，该设计能够在130 keV能量范围内产生亚100 fs的高电荷电子束团。我们的模拟表明，我们提出的半单元射频腔能够产生137 keV、均方根（rms）脉宽为27 fs（半高宽为60 fs）、10个电子束团，其均方根光斑尺寸为276 µm，横向相干长度为2.0 nm。所需的运行功率为9.2 kW，显著低于传统射频腔设计，这是一个关键的设计特点。这种电子源进一步依赖于阴极处的高电场梯度，以同时加速和压缩电子束团，从而为原子分辨动力学开辟新的时空分辨率领域。
