Tech Area / Field. Brief Description of TechnologyNovel physical phenomena, namely superradiance from single electron bunches

• PHY-RAW: Physics / Radiofrequency Waves

Brief Description of Technology
Novel physical phenomena, namely superradiance from single electron bunches, was suggested for use in the generation of intense microwave pulses of ultrashort duration. Different types of superradiance were studied experimentally and in association with several different types of emission — including Cherenkov, cyclotron and bremstrahlung mechanisms — when the electron bunches were passed through slow wave structures, rotated in a magnetic field or oscillated in wiggler fields. Megawatt power level millimeter-wave pulses of uniquely short duration (0.3-0.5 ns) have been generated.

Superradiance occurs in a specific situation when the electron pulse duration significantly exceeds the operating wavelength (otherwise the radiation is effectively spontaneous), but is less than the interaction length (in contrast with traditional mechanisms of stimulated emission of quasi-continuous electron beams that are used extensively in microwave electronics). Coherent emission from the entire electron pulse can only take place when a self-bunching mechanism typical for stimulated emission develops.

Legal Aspects
None in this research.

Special Facilities in Use and Their Specifications
The unique table-top RADAN 303 accelerator with a subnanosecond slicer was used to inject typically 0.3-0.5 ns, 0.2-1 kA, 250 keV electron pulses. These electron pulses were generated from a magnetically insulated coaxial diode which utilized a cold explosive emission cathode. The accelerator is capable of repetitive operation, up to a 100 pps regime.

Scientific Papers
N.S.Ginzburg, I.V.Zotova and A.S.Sergeev, "Cyclotron Superradiance of a moving electron swarm under group synchronisation conditions,” Sov. JETP Lett, Vol. 60, No.7, pp. 513-515 (1994).

N.S.Ginzburg, I.V.Zotova, I.V.Konoplev, A.S.Sergeev, V.G.Shpak, S.A.Shunailov, M.R.Ul'maskulov, and M.I.Yalandin, "Experimental observation of cyclotron superradiance," Sov. JETP Lett., Vol. 63, No.5, pp. 331-335 (1996).

N.S.Ginzburg, I.V.Zotova, I.V.Konoplev, A.S.Sergeev, A.D.R.Phelps, A.W.Cross, S.J.Cooke, V.G.Shpak, S.A.Shunailov, M.R.Ul'maskulov, and M.I.Yalandin, "Experimental observation of cyclotron superradiance under group synchronism conditions," Phys.Rev.Lett, Vol.78, No.12, pp.2365-2368 (1997).

N.S.Ginzburg, A.S.Sergeev, I.V.Zotova, Yu.N.Novozilova, N.Yu. Peskov, I.V.Konoplev, A.D.R.Phelps, A.W.Cross, S.J.Cooke, P.Aitken, V.G.Shpak, M.I.YalandinS.A.Shunailov, M.R.Ul'maskulov, and M.I.Yalandin, "Experimental observation of superradiance in millimeter-wave band," Nucl.Inst. and Meth. in Phys.Res.A, in press (1997).

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