Amberg, M.

Aulenbacher, K.

Barth, W.

Basten, M.

Busch, M.

Dziuba, F.

Heilmann, M.

Mickat, S.

Mäder, D.

Podlech, H.

GSI Repository

Status of the superconducting 217 MHz CH-cavity* M. Basten#,1, M. Amberg1,3, K. Aulenbacher3,4, W. Barth2,3, M. Busch1, F. Dziuba1, M. Heilmann2,    D. Mäder1, S. Mickat2,3, H. Podlech1 1Frankfurt Universtiy, 60438 Frankfurt, Germany; 2GSI Helmholtzzentrum, 64291 Darmstadt, Germany; 3Helmholtz-Institut Mainz (HIM), 55099 Mainz, Germany; 4KPH Mainz University, 55128 Mainz, GermanyPresently the demonstrator for the sc cw-LINAC at GSI is under construction and its successful beam operation will be the first milestone realizing the new sc cw-LINAC at GSI [1]. The construction of an advanced demonstrator will be the second milestone towards the sc cw-LINAC at GSI. The presently design of the sc cw-LINAC consists of the demonstrator as first cavity and 4 to 5 additional cryomodules with 2 CH-cavities per cryomodule [2,3]. The design of the advanced demonstrator will be used for all cavities in the sc cw-LINAC after the demonstrator. The cavity is designed and optimized for high power ap-plications, consisting of 8 accelerating cells. The design gradient is 5 MV/m. Its frequency is the second harmonic of the High Charge Injector (HLI) at GSI, Darmstadt. Table 1 shows the main parameters of the sc 217 MHz CH-cavity. In Figure 1 the layout of the sc 217 MHz CH-cavity is depicted. Cavity Design The design of the cavity is based on 8 equidistant gaps without girders and with stiffening brackets at the front and end cap to reduce pressure sensitivity. The new de-sign avoids girders because they lead to high fabrication costs and extended fabrication duration. Additionally the girders reduce the mechanical stability of the cavity caused by a break of the cylindrical symmetry. The de-sign of the advanced demonstrator without girders is cy-lindrically symmetrical which leads to significantly high-er stability. Additionally the stiffening brackets at both ends of the cavity increase the mechanical stability of the cavity so that the pressure sensitivity is below 5 Hz/mbar.  Parameter Unit  β  0.069 Frequency MHz 215.5 Accelerating cells  8 Length (βλ-definition) mm 381.6 Cavity diameter mm 412 Cell length mm 47.7 Aperture diameter mm 30 Static tuner  3 Dynamic bellow tuner  2 Wall thickness mm 3-4 Accelerating gradient MV/m 5 Ep/Ea  5.2 Bp/Ea mT/(MV/m) 8.5 G Ω 51 Ra/Q0  1045 Table 1: Specifications of the 217 MHz CH-cavity   Figure 1: Layout of the sc 217 MHz CH-cavity. Status The basic design of the 217 MHz CH-cavity was fin-ished in 2014. Several simulations with CST-Microwave-Studio have been performed to determine parameters as the optimum drift tube length, optimum stem width and cavity diameter [4]. The missing girders in the 217 MHz-cavity require a new design for the dynamic and static tuners. Because of that many simulations concerning the layout and performance of the bellow tuners have been performed to find the optimum geometry. The call for tender started in december 2014 and will end on february 2015. So the communication with the company will start in february 2015 and will be followed by the production start. References [1] F. Dziuba, M. Amberg, K. Aulenbacher, W. Barth, M. Busch, H. Podlech, U. Ratzinger, S. Mickat, Su-perconducting CH Cavities for Heavy Ion Accelera-tion, in Proc. of IPAC'13, Shanghai, China, p. 3794-3796 (2013)  [2] W. Barth, K. Aulenbacher, F. Dziuba, M. Amberg, V. Gettmann, S. Mickat, H. Podlech, U. Ratzinger, Further R&D for a New Superconducting cw Heavy Ion Linac@GSI, in Proc. of IPAC'14, Dresden, Ger-many, p. 3211-3213 (2014) [3] H. Podlech, Proposal for a Superconducting 217 MHz CH-Cavity, institute report: IAP-ACCC-01122013 (2013) [4] CST Microwave Studio, http://www.cst.com  ___________________________________________  * Work supported by HIM, GSI #Basten@iap.uni-frankfurt.de FG-GENERAL-03 GSI SCIENTIFIC REPORT 2014420 DOI:10.15120/GR-2015-1-FG-GENERAL-03

Status of the superconducting 217 MHz CH-cavity

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Status of the superconducting 217 MHz CH-cavity

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