Self-amplification of coherent spontaneous emission in a cherenkov free-electron maser

• Published in: Physical review letters Vol. 84; no. 11; pp. 2393 - 2396
• Main Authors: Wiggins, SM, Jaroszynski, DA, McNeil, BW, Robb, GR, Aitken, P, Phelps, AD, Cross, AW, Ronald, K, Ginzburg, NS, Shpak, VG, Yalandin, MI, Shunailov, SA, Ulmaskulov, MR
• Format: Journal Article
• Language: English
• Published: United States 13-03-2000
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.84.2393

Ultrashort pulses of microwave radiation have been produced in a dielectric-lined Cherenkov free-electron maser (FEM) amplifier. An intense initial seed pulse, due to coherent spontaneous emission (CSE), arises at the leading edge of the electron pulse. There is evidence to show that 3-4 cycle spikes are produced through the amplification of these seed pulses. A strong dependence of the start-up power on the rise time of the electron pulse has been found. The experimental results are verified by a theoretical analysis. Our study shows that amplification in a FEM amplifier is always initiated by CSE arising from the edge of the electron pulse when the rise time is comparable to the electromagnetic wave period.