Hähnel, H.

Mickat, S.

Ratzinger, U.

Tiede, R.

GSI Repository

Development of a MEBT Design to replace current UNILAC Superlens∗H. Ha¨hnel†1, U. Ratzinger1, R. Tiede1, and S. Mickat21IAP, Goethe University, Frankfurt, Germany; 2GSI, Darmstadt, GermanyAs part of the UNILAC upgrade, a new MEBT sectionis proposed [1]. It will provide improved matching to theIH-DTL and therefore a significant reduction in emittancegrowth and lossless transmission at 20.75 mA U4+. Thisway the FAIR requirement of 18 mA U4+ behind the IH-DTL can easily be reached with the new MEBT. The designcomprises of two quadrupole triplet lenses and a two-gapbuncher cavity (see Figure 1), providing more flexibilitythan the existing “Superlens” MEBT [2]. This layout al-lows to reuse the existing XY-steerer, the vacuum valve andthe diagnostics box. It also provides some spare room foradditional/redesigned components.IH-DTLRFQtriplet lens triplet lensbuncherXY-steerervalvediag.Figure 1: Layout of the proposed MEBT section.The overall length of the new MEBT is 1.82 m which is0.4 m longer than the existing MEBT section. The posibil-ity of providing the extra length by moving the IH-DTL iscurrently being investigated.At 20.75 mA the simulated losses in the Superlens usingthe RFQ output distribution after the 2008 upgrade amountto 12 % [1][3]. Losses are caused by insufficient transversalfocusing and the limiting aperture of the Superlens.Figure 2: Output distribution of new MEBT with IH-DTLacceptance as reported in [4].The new MEBT ensures transversal and longitudinal fo-cusing matched to the IH-DTL input acceptance (Figure 2).By using two quadrupole triplet lenses, the design providessome flexibility to compensate changes in the input distri-∗Work supported by BMBF 05P12RFRB9† haehnel@iap.uni-frankfurt.debution. The gap voltage of the buncher cavity can also beadjusted if necessary to change longitudinal focusing.Figure 3: Envelopes of new MEBT and IH1 at 20.75 mA.Table 1: Prestripper output parameter comparison.SL MEBT New MEBTTotal length 1.4 m 1.82 mDesign current 16.5 mA 20.75 mADesign A/q 65 59.5 (U4+)MEBT-out for 20.75 mA U4+Transmission 87.94 % 100 %ǫrms [mm mrad] x:0.108 y:0.09 x:0.072 y:0.073ǫrms [keVu ns] 0.389 0.358IH-outTransmission 85.7 % 100 %ǫrms [mm mrad] x:0.162 y:0.158 x:0.117 y:0.138ǫrms [keVu ns] 1.279 0.517A comparison of output parameters of the prestrippersection is made in Table 1 showing a reduction of rmsemittance growth of 27.8 %, 12.7 % for x-x’,y-y’ and 59.6% for the longitudinal plane behind the IH-DTL. Simula-tions with currents from 10 to 20.75 mA U4+ show loss-less transmission for the MEBT+IH and even low losses at35 mA U4+. Upgrading the MEBT section would signifi-cantly improve the overall UNILAC efficiency and provideflexibility for high current operation which is required forFAIR.References[1] H. Ha¨hnel, U. Ratzinger, R. Tiede, MOPP062, Proc.LINAC2014[2] U. Ratzinger, R. Tiede, MOP31, Proc. LINAC96[3] All simulations were performed with LORASR.[4] R. Tiede, “HSI IH-DTL Acceptance Studies”, Talk at IAP-GSI UNILAC-Upgrade meeting, Frankfurt, January 16th,2014FG-UNILAC-07 GSI SCIENTIFIC REPORT 2014402 DOI:10.15120/GR-2015-1-FG-UNILAC-07

Development of a MEBT Design to replace current UNILAC Superlens

http://repository.gsi.de/record/184119/files/FG-UNILAC-07.pdf

Development of a MEBT Design to replace current UNILAC Superlens

Abstract

Similar works

Full text

Available Versions

GSI Repository