Author: Gover, A.
Paper Title Page
TUP007 Spectral Limits and Frequency Sum-rule of Current and Radiation Noise Measurement 362
 
  • A. Gover, R. Ianconescu
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  • A. Nause
    UCLA, Los Angeles, USA
  
  Funding: This research was supported by a grant from the United States-Israel Binational Science Foundation(BSF), Jerusalem, ISRAEL
The cur­rent noise spec­trum of an elec­tron beam is gen­er­ally con­sid­ered white and ex­pressed by the shot-noise for­mula (eI0). It is pos­si­ble to con­trol the spec­tral en­ergy of a ran­dom elec­tron beam cur­rent by lon­gi­tu­di­nal space charge mi­cro­dy­nam­ics and dis­per­sive trans­port. Both noise sup­pres­sion (rel­a­tive to eI0)[1,2] and noise en­hance­ment[3] have been demon­strated, ex­hibit­ing sub/su­per-Pois­son­ian par­ti­cle dis­tri­b­u­tion sta­tis­tics, re­spec­tively. We pre­sent a gen­eral the­ory for the cur­rent noise of an e-beam and its ra­di­a­tion emis­sion in the en­tire spec­trum. The mea­sur­able cur­rent noise spec­trum is not white. It is cut-off at high fre­quen­cies, lim­ited by the mea­sure­ment length and the beam axial mo­men­tum spread (fun­da­men­tally lim­ited by quan­tum un­cer­tainty). We show that under cer­tain con­di­tions the cur­rent noise spec­trum sat­is­fies a fre­quency sum-rule: ex­hibit­ing noise en­hance­ment in one part of the spec­trum when sup­pressed at an­other part and vice versa. The spon­ta­neous emis­sion (ra­di­a­tion noise) into a sin­gle ra­di­a­tion mode or sin­gle di­rec­tion in any scheme (OTR, Un­du­la­tor etc.) is sub-ra­di­ant when the beam cur­rent is sub-Pois­son­ian and vice versa, but the sum-rule does not apply. 		 
 
TUP064 Narrow Linewidth, Chirp-Control and Radiation Extraction Optimization in an Electrostatic Accelerator FEL Oscillator 509
 
  • H. S. Marks, A. Gover, H. Kleinman, J. Wolowelsky
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  • D. Borodin, M. Einat, M. Kanter, Y. Lasser, Yu. Lurie
    Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel
  
  In re­cent years the elec­tro­sta­tic ac­cel­er­a­tor FEL based in Ariel has un­der­gone many up­grades. By vary­ing the ac­cel­er­at­ing po­ten­tial the res­onator al­lows las­ing be­tween 95-110 GHz. It is now pos­si­ble to re­motely con­trol the out­put re­flec­tiv­ity of the res­onator and thereby vary both the power built up in the res­onator and that emit­ted. This has al­lowed fine con­trol over the power for dif­fer­ent user ex­per­i­ments. A volt­age ramp­ing de­vice has been in­stalled at the res­onator/wig­gler to cor­rect drops in volt­age which occur due to elec­trons strik­ing the walls of the beam line. This has al­lowed sta­ble pulses of just over 50 μs with a chirp rate of ~80 kHz/μs.  
 
TUP081 Configuration and Status of the Israeli THz Free Electron Laser 553
 
  • A. Friedman, N. Balal, V.L. Bratman, E. Dyunin, Yu. Lurie, E. Magori
    Ariel University, Ariel, Israel
  • A. Gover
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  
  Funding: This project is funded in part by Israel Ministry of Defense.
A THz FEL is being built in Ariel Uni­ver­sity. This pro­ject is a col­lab­o­ra­tion be­tween Ariel Uni­ver­sity, and Tel Aviv Uni­ver­sity. Upon com­ple­tion it is in­tended to be­come a user fa­cil­ity. The FEL is based on a com­pact photo cath­ode gun (60 cm) that will gen­er­ate an elec­tron beam at en­er­gies of 4.5 - 6.5 MeV. The pulses are planned to be of 300 pico Coulomb for a sin­gle pulse, and of up to 1.5 nano Coulomb for a train of pulses. The FEL is de­signed to emit ra­di­a­tion be­tween 1 and 5 THz. It is planned to op­er­ate in the super ra­di­ance regime. The con­fig­u­ra­tion of the en­tire sys­tem will be pre­sented, as well as the­o­ret­i­cal and nu­mer­i­cal re­sults for the an­tic­i­pated out­put of the FEL, which is in ex­cess of 150 KW in­stan­ta­neous power. The bunch­ing of the elec­tron bean will be achieved by mix­ing two laser beams on the photo-cath­ode. The com­pres­sion of the beam will be achieved be in­tro­duc­ing an en­ergy chierp to the beam and pass­ing it through a he­li­cal chi­cane. We plan on com­press­ing the sin­gle pulse to less than 150 femto sec­onds. The sta­tus of the pro­ject at the time of the con­fer­ence will be pre­sented. 		 
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