Author: Modin, P.
Paper Title Page
TUP036 Observation of Smith-Purcell Radiation at 32 GHz from a Multi-channel Grating with Sidewalls 470
 
  • J.T. Donohue
    CENBG, Gradignan, France
  • J. Gardelle, P. Modin
    CEA, LE BARP cedex, France
  
  In a demon­stra­tion ex­per­i­ment at 5 GHz, we found co­pi­ous emis­sion of co­her­ent Smith-Pur­cell (SP) ra­di­a­tion at the fun­da­men­tal fre­quency of the evanes­cent sur­face wave, when the grat­ing had side­walls. Reach­ing higher fre­quen­cies re­quires a re­duc­tion in the size of the grat­ing, which leads to a con­sid­er­able re­duc­tion in power. To par­tially com­pen­sate this, we sug­gested su­per­pos­ing sev­eral copies of the re­duced grat­ing in par­al­lel. A test of this con­cept has been per­formed with a seven-chan­nel grat­ing, at a fre­quency near 32 GHz. The SP ra­di­a­tion sig­nals were ob­served di­rectly with a fast os­cil­lo­scope. Power lev­els were of order 5 kW, in fair agree­ment with three-di­men­sional sim­u­la­tions made using the code "MAGIC".  
 
WEA04 First Lasing from a High Power Cylindrical Grating Smith-Purcell Device 611
 
  • H. Bluem, R.H. Jackson, J.D. Jarvis, A.M.M. Todd
    AES, Medford, New York, USA
  • J.T. Donohue
    CENBG, Gradignan, France
  • J. Gardelle, P. Modin
    CEA, LE BARP cedex, France
  
  Funding: Work supported by ONR under Contract No. N00014-10-C-0191 and N62909-13-1-N62.
Many ap­pli­ca­tions of THz ra­di­a­tion re­main im­prac­ti­cal or im­pos­si­ble due to an ab­sence of com­pact sources with suf­fi­cient power. A source where the in­ter­ac­tion oc­curs be­tween an an­nu­lar elec­tron beam and a cylin­dri­cal grat­ing is ca­pa­ble of gen­er­at­ing high THz power in a very com­pact pack­age. The strong beam bunch­ing gen­er­ates sig­nif­i­cant power at the fun­da­men­tal fre­quency and har­mon­ics. A col­lab­o­ra­tion be­tween Ad­vanced En­ergy Sys­tems and CEA/CESTA has been on­go­ing in per­form­ing proof-of-prin­ci­ple tests on cylin­dri­cal grat­ing con­fig­u­ra­tions pro­duc­ing mil­lime­ter wave ra­di­a­tion. First las­ing was achieved in such a de­vice. Fur­ther ex­per­i­ments per­formed with a 6 mm pe­riod grat­ing pro­duced fun­da­men­tal power at 15 GHz, sec­ond har­monic power at 30 GHz and al­though not mea­sured, sim­u­la­tions show mean­ing­ful third har­monic power at 45 GHz. Com­par­i­son with sim­u­la­tions shows very good agree­ment and high con­ver­sion ef­fi­ciency. Planned ex­per­i­ments will in­crease the fre­quency of op­er­a­tion to 100 GHz and be­yond. On­go­ing sim­u­la­tions in­di­cate ex­cel­lent per­for­mance for a de­vice op­er­at­ing at a fun­da­men­tal fre­quency of 220 GHz with re­al­is­tic beam pa­ra­me­ters at 10 kV and sim­ple ex­trac­tion of the mode. 		 
slides icon Slides WEA04 [2.344 MB]