AbstractThe goal of this report is to investigate the properties of an electron beam, generated by photoionization of hydrogen and alkali atoms in an external electric field. Here a quantum mechanical simulationcis set up in parabolic coordinates, where the time independent Schrödinger equation is separable. Acriterion on the existence of resonant states has been shown and a scaling law on total number of resonances as function of electric field is obtained.
The model has been used to describe single and two-step photoionization for both hydrogen and alkali atoms. The calculated photoionization crosssection is compared with other simulations and measurement, which show good agreement. It has also been shown that the crosssection varies as function of polarization angle in a sinusoidal fashion.
Based on sharp peaks in the photoionization spectrum it is argued, and later shown in measurement and simulation that is it possible to isolate a specific parabolic state. Based on geometry it is shown that the states with highest crosssection have the lowest beam divergence.
In the case of monochromatic ionization the outgoing electron beam is expected to show a pattern consisting of the product of a fast oscillation and slowly oscillating envelope, when it arrives at a detector.
Finally a comparison between classical and quantum mechanically calculated transverse velocity distribution at the end of an accelerator is conducted. Resulting in that off-resonance both models show similar features, whereas on-resonance the quantum and classical models differ significantly.
|Date of Award||14 Aug 2018|
|Supervisor||O.J. (Jom) Luiten (Supervisor 1)|
Electron beam generation by field dependent photoionization
Schoutrop, C. (Author). 14 Aug 2018
Student thesis: Master