Author: Stoltz, P.
Paper Title Page
MOPWA056 Spectra of Coherent Smith-Purcell Radiation Observed from Short Electron Bunches: Numerical and Experimental Studies 801
 
  • F. Bakkali Taheri, G. Doucas, I.V. Konoplev, A. Reichold
    JAI, Oxford, United Kingdom
  • H.L. Andrews
    LANL, Los Alamos, New Mexico, USA
  • R. Bartolini
    Diamond, Oxfordshire, United Kingdom
  • V. Bharadwaj, C.I. Clarke
    SLAC, Menlo Park, California, USA
  • N. Delerue
    LAL, Orsay, France
  • N. Fuster Martinez
    IFIC, Valencia, Spain
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work performed [in part] under DOE Contract DE-AC02-7600515
There is a sig­nif­i­cant in­ter­est in the de­vel­op­ment of com­pact par­ti­cle ac­cel­er­a­tors within re­search areas in­clud­ing X-ray and THz (T-ray) sources of ra­di­a­tion, par­ti­cle physics and med­ical sci­ences. To sup­port the progress in these areas, non-in­va­sive, elec­tron beam di­ag­nos­tics that are ca­pa­ble of mea­sur­ing a sin­gle fem­tosec­ond elec­tron bunch are re­quired. At the cur­rent stage such beam di­ag­nos­tics for fem­tosec­ond-long elec­tron bunches are still not avail­able. The goal of the work pre­sented is to un­der­stand the spec­tral char­ac­ter­is­tics of co­her­ent Smith-Pur­cell ra­di­a­tion to en­able its quick and re­li­able in­ter­pre­ta­tion in­clud­ing the lon­gi­tu­di­nal pro­file re­con­struc­tion of elec­tron bunches. The re­search pre­sented com­prises re­sults from nu­mer­i­cal mod­el­ling and ex­per­i­men­tal stud­ies. Using the nu­mer­i­cal data, we dis­cuss the ra­di­ated spec­tra de­pen­dence on the elec­tron bunch pro­file and analyse the re­sults. We also dis­cuss the ex­per­i­men­tal data and com­pare it with the­o­ret­i­cal pre­dic­tions. 		 
 
MOPWO068 Simulating Electron Cloud Evolution using Modulated Dielectric Models 1043
 
  • S.A. Veitzer, P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920)
Elec­tron clouds can pose a se­ri­ous threat to ac­cel­er­a­tor per­for­mance, and un­der­stand­ing cloud buildup and the ef­fec­tive­ness of dif­fer­ent mit­i­ga­tion tech­niques can pro­vide cost-sav­ing im­prove­ments in ac­cel­er­a­tor de­sign and fab­ri­ca­tion. Mi­crowave di­ag­nos­tics of elec­tron clouds are a non-de­struc­tive way to mea­sure cloud buildup, but it is very dif­fi­cult to mea­sure the cloud den­sity from spec­tral sig­nals alone. Mod­el­ing trav­el­ling-wave rf di­ag­nos­tics is very hard be­cause of the large range of spa­tial and tem­po­ral scales that must be re­solved to sim­u­late spec­tra. New nu­mer­i­cal mod­els have been used to gen­er­ate syn­thetic spec­tra for elec­tron clouds when the cloud den­sity is not chang­ing, and re­sults have been com­pared to the­o­ret­i­cal re­sults. Here we use di­elec­tric mod­els to gen­er­ate spec­tra for clouds that evolve over many bunch cross­ings. We first per­form de­tailed sim­u­la­tions of cloud buildup using ki­netic par­ti­cle mod­els, and then use an equiv­a­lent plasma di­elec­tric model cor­re­spond­ing to this den­sity, at a finer time res­o­lu­tion, to com­pute spec­tra. The sta­bil­ity and ac­cu­racy of di­elec­tric mod­els that spec­tra can be ac­cu­rately de­ter­mined in these very long timescale sim­u­la­tions. 		 
 
TUPEA071 THz Bench Tests of a Slab-symmetric Dielectric Waveguide 1292
 
  • F. Lemery, H. Panuganti, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • D. Mihalcea, P. Piot
    Fermilab, Batavia, USA
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
Di­elec­tric-lined wave­guides (DLW) are be­com­ing more pop­u­lar for beam dri­ven ac­cel­er­a­tion ap­pli­ca­tions. An ex­per­i­ment to demon­strate beam-dri­ven ac­cel­er­a­tion using a slab-sym­met­ric di­elec­tric-lined wave­guide dri­ven by a flat beam is in prepa­ra­tion at the Ad­vanced Su­per­con­duct­ing Test Ac­cel­er­a­tor (ASTA) at Fer­mi­lab. In this paper we char­ac­ter­ize the struc­ture using a THz pulse ob­tained from op­ti­cal rec­ti­fi­ca­tion using an am­pli­fied laser pulse. After prop­a­ga­tion through the DLW struc­ture, the THz pulse is an­a­lyzed using a Michel­son in­ter­fer­om­e­ter and sin­gle-shot elec­tro-op­ti­cal imag­ing. Data for var­i­ous gap size will be pre­sented. 		 
 
TUPEA072 Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator 1295
 
  • F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot, Y.-E. Sun
    Fermilab, Batavia, USA
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Ad­vanced Su­per­con­duct­ing Test Ac­cel­er­a­tor (ASTA), presently under con­struc­tion at Fer­mi­lab, will pro­duce high-charge (~<3 nC) elec­tron bunches with en­er­gies rang­ing from 50 to even­tu­ally 750 MeV. The fa­cil­ity is based on a su­per­con­duct­ing linac ca­pa­ble of pro­duc­ing up to 3000 bunches in 1-ms macropulses re­peated at 5 Hz. In this paper we ex­plore the use of a short di­elec­tric-lined-wave­guide (DLW) linac to sig­nif­i­cantly in­crease the bunch en­ergy. The method con­sists in (1) using ad­vanced phase space ma­nip­u­la­tion tech­niques to shape the beam dis­tri­b­u­tion and en­hance the trans­former ratio, and (2) op­ti­mize the gen­er­a­tion and ac­cel­er­a­tion of a low-charge wit­ness bunches. Start-to-end sim­u­la­tions of the pro­posed con­cept are pre­sented. This DLW mod­ule could also be used to test some as­pects of a re­cently pro­posed con­cept for a multi­user short-wave­length free-elec­tron laser uti­liz­ing a se­ries of DLW linacs*.
* C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012). 		 
 
TUPEA073 Performances of VORPAL-GPU Slab-symmetric DLW 1298
 
  • F. Lemery, K. Duffin, N. Karonis, D. Mihalcea, P. Piot, J. Winans
    Northern Illinois University, DeKalb, Illinois, USA
  • P.J. Mullowney, P. Stoltz
    Tech-X, Boulder, Colorado, USA
  • P. Piot
    Fermilab, Batavia, USA
  
  Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later)
GPU-based com­put­ing has gained pop­u­lar­ity in re­cent years due to its grow­ing soft­ware sup­port and greater pro­cess­ing ca­pa­bil­i­ties than its CPU coun­ter­part.  GPU com­put­ing was re­cently added in the fi­nite-dif­fer­ence time-do­main pro­gram VOR­PAL. In this paper we carry elec­tro­mag­netic sim­u­la­tions and op­ti­miza­tion of a flat beam pass­ing through a slab-sym­met­ric di­elec­tric-lined wave­guide (DLW). We use this sim­u­la­tion model to ex­plore the scal­ing of the GPU ver­sion of VOR­PAL on a new TOP1000-grade hy­brid GPU/CPU com­puter clus­ter avail­able at North­ern Illi­nois Uni­ver­sity.