Author: Ratzinger, U.
Paper Title Page
MOPAB19 Space-Charge Compensation of Intense Ion Beams by Nonneutral Plasma Columns 67
 
  • K. Schulte, M. Droba, O.K. Kester, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger, K. Zerbe
    IAP, Frankfurt am Main, Germany
  • O.K. Kester
    GSI, Darmstadt, Germany
  
  Gabor lenses were con­ceived to focus a pass­ing ion beam using the elec­tri­cal field of a con­fined non­neu­tral plasma col­umn. Be­side its ap­pli­ca­tion as fo­cus­ing de­vice, in Gabor lenses space-charge ef­fects can be stud­ied in de­tail. The in­flu­ence of the elec­tron dis­tri­b­u­tion on emit­tance and space-charge dom­i­nated ion beams was in­ves­ti­gated in beam trans­port ex­per­i­ments*. In this con­tri­bu­tion we want to em­pha­size one re­sult of these ex­per­i­ments. The mea­sure­ments in­di­cated a strong con­tri­bu­tion of sec­ondary elec­trons on beam dy­nam­ics. Sec­ondary elec­trons are pro­duced within the trans­port chan­nel, par­tic­u­larly by in­ter­ac­tion of the beam with the sur­face of the slit-grid emit­tance scan­ner. This might lead to an in­crease of the fill­ing de­gree and to an im­proved fo­cus­ing per­for­mance of the lens. As­sum­ing that the loss and pro­duc­tion rates within the lens vol­ume and the trans­port chan­nel de­ter­mine the equi­lib­rium state of the non­neu­tral plasma col­umn, the elec­tron cloud was char­ac­ter­ized as a func­tion of the ex­ter­nal fields and the resid­ual gas pres­sure in small-scale table top ex­per­i­ments. In this con­tri­bu­tion ex­per­i­men­tal re­sults will be pre­sented in com­par­i­son with nu­mer­i­cal sim­u­la­tions.
* K. Schulte, “Studies on the focusing performance of a Gabor lens depending on nonneutral plasma properties”, PhD thesis, 2013. 		 
 
WEO1AB01 Upgrade of the UNILAC for FAIR 245
 
  • L. Groening, A. Adonin, X. Du, R. Hollinger, S. Mickat, A. Orzhekhovskaya, B. Schlitt, G. Schreiber, H. Vormann, C. Xiao
    GSI, Darmstadt, Germany
  • H. Hähnel, U. Ratzinger, R. Tiede
    IAP, Frankfurt am Main, Germany
  
  The UNI­ver­sal Lin­ear Ac­cel­er­a­tor (UNI­LAC) at GSI has served as in­jec­tor for all ion species from pro­tons for ura­nium for the past four decades. Es­pe­cially its 108 MHz Al­varez type DTL pro­vid­ing ac­cel­er­a­tion from 1.4 MeV/u to 11.4 MeV/u has suf­fered from ma­te­r­ial fa­tigue. The DTL will be re­placed by a com­pletely new sec­tion with al­most the same de­sign pa­ra­me­ters, i.e. pulsed cur­rent of up to 15 mA of 238U28+ at 11.4 MeV/u. How­ever, op­er­a­tion will be re­stricted to low beam duty cy­cles as 200 μs at 10 Hz. Since preser­va­tion of beam qual­ity is manda­tory, a reg­u­lar fo­cus­ing lat­tice, as along an Al­varez sec­tion for in­stance, is aimed for. A new source ter­mi­nal & LEBT ded­i­cated to op­er­a­tion with 238U4+ is under de­sign. The ura­nium sources need to be up­graded in order to pro­vide in­creased beam bril­liances and for op­er­a­tion at 3 Hz. Re­vi­sion of the sub­se­quent 36 MHz RFQ elec­trode de­sign has started as well as the lay­out ac­tiv­i­ties of the sec­tion pro­vid­ing tran­si­tion from the 36 MHz sec­tion to the 108 MHz DTL.  
slides icon Slides WEO1AB01 [1.325 MB]  
 
WEO4LR02 The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport 304
 
  • D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
    IAP, Frankfurt am Main, Germany
  
  A new non-rel­a­tivis­tic, elec­tro­sta­tic Par­ti­cle-in-Cell code named ben­der has been im­ple­mented to fa­cil­i­tate the in­ves­ti­ga­tion of low-en­ergy beam trans­port sce­nar­ios. In the case of high-in­ten­sity beams, space-charge com­pen­sa­tion re­sult­ing from the ac­cu­mu­la­tion of sec­ondary par­ti­cles - elec­trons for pos­i­tively charged ion beams - is an im­por­tant ef­fect. It has been shown, that the dis­tri­b­u­tion of com­pen­sa­tion elec­trons can have a sig­nif­i­cant in­flu­ence on the beam and lead to an emit­tance growth. To im­prove the un­der­stand­ing of the dy­nam­ics of the com­pen­sa­tion and the re­sul­tant self-con­sis­tent steady state, ion­iza­tion of resid­ual gas as well as sec­ondary elec­tron pro­duc­tion on sur­faces have been im­ple­mented and used to study a num­ber of test sys­tems. We will pre­sent first re­sults of these com­pen­sa­tion stud­ies as well as fur­ther ap­pli­ca­tions of the code, among them the chop­per sec­tion of the fu­ture FRANZ fa­cil­ity [1].
* C. Wiesner et al., Experimental Performance of an E×B Chopper System, Proc. of IPAC 2014, THPME015 		 
slides icon Slides WEO4LR02 [5.373 MB]