Abstract-Terahertz Undulator Radiation of Stabilized Dense Electron Beams

I. V. BandurkinI,  S. Kurakin, Yu. S. Oparina, A. V. Savilov, V. L. Bratman, N. Balal, Yu. Lurie

https://link.springer.com/article/10.3103%2FS1062873818120262

Dense short electron bunches produced by state-of-the-art photoinjector-based accelerators are used to create sources of powerful electromagnetic pulses of terahertz frequency range based on spontaneous coherent emission by these bunches. However, there is a problem of stabilizing the phase dimension of a bunch along the space of electron wave interaction. In this work, two means of such stabilization are considered that are based on using the intrinsic electromagnetic fields (quasi-static and radiation) of bunches.

Abstract-Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

N. Balal¹, I. V. Bandurkin², V. L. Bratman^1,2, E. Magory¹ and A. V. Savilov^2,3
 HIDE AFFILIATIONS
1 Ariel University, Ariel 40700, Israel
2 Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950, Russia
3 Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950, Russia
Appl. Phys. Lett. 107, 163505 (2015); http://dx.doi.org/10.1063/1.4934495

http://scitation.aip.org/content/aip/journal/apl/107/16/10.1063/1.4934495

It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniformmagnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.