Paper 
Title 
Page 
MOPPH017 
1D Linear Intensity Spiking Evolution in a Single Shot of a SASE FEL

54 

 V. Petrillo
Universita' degli Studi di Milano, Milano
 L. Serafini, C. Maroli
INFNMilano, Milano



The analysis is based on the 1D MaxwellLorentz equations which are reduced to the usual averaged linear equation in the limit of vanishingly small radiation field A(z,t) and average length lm. It is shown that if this equation is solved with initial shot noise conditions in which the widths of the spikes and the average distance between successive spikes are both uniformly smaller than the cooperation length Lc, it may lead to large amplitude coherent signals. The intensity spiking RMS relative amplitude decreases from the 100% values it has at t=0, down to values of the order or less than 0.1% in time intervals from ten to twenty gain times.


TUPPH012 
Compact Xray FreeElectronLaser Based on an Optical Undulator

244 

 A. Bacci, C. Maroli, A. R. Rossi, L. Serafini
INFNMilano, Milano
 V. Petrillo
Universita' degli Studi di Milano, Milano
 P. Tomassini
INFNPisa, Pisa



The interaction between a very high brightness electron beam and a relativistically intense optical laser pulse produces X rays via coherent Thomson back scattering with FEL collective amplification. The phenomenon is, however, very selective, so that the characteristics of both electron and laser beam must satisfy tight requirements in terms of beam current, emittance, energy spread and laser amplitude stability within the pulse. The threedimensional equations governing the radiation phenomena have been studied in both linear and non linear regime and solved numerically for the particularly interesting values of wavelengths of 1 Ang, 1 nm and 12 nm. The performance of the collective Thomson source has been compared with that of an equivalent static undulator. A set of scaling laws ruling the phenomenon is also presented. The possibility of using an electron beam produced via LWFA in the bubble regime is investigated.

