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.