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TY - CONF AU - Ramberger, S. AU - Khalvati, M.R. ED - Yamazaki, Yoshishige ED - Facco, Alberto ED - McCausey, Amy ED - Schaa, Volker RW TI - The DTL Post Coupler - An Ingenious Invention Turns 50 J2 - Proc. of LINAC2016, East Lansing, MI, USA, 25-30 September 2016 C1 - East Lansing, MI, USA T2 - Linear Accelerator Conference T3 - 28 LA - english AB - In September 1967, the patent for "A method and device for stabilization of the field distribution in drift tube linac" has been filed by Edward A. Knapp, Donald A. Swenson, and James M. Potter of Los Alamos National Laboratory. It is this invention which to a good part led to the success of highly efficient Alvarez drift tube linacs (DTLs) in that it considerably reduces field errors. The explanation for why the post coupler when tuned correctly has such a strong stabilizing effect has been given at the time in an accompanying paper by describing the modal confluence of the accelerating mode band with the post-coupler mode band, turning a comparatively sensitive 0-mode structure into a stable pi/2-mode like structure. As ingenious as the invention of the post-coupler appears, as poor has been the way of finding its optimum length by relying mainly on trial and error. With the design of the Linac4 DTL at CERN, a new technique has been derived by a DTL equivalent circuit model. Understanding stabilization on an almost cell by cell level provides a new way of optimizing post-couplers of an entire structure with few measurements and even without the extraction of the circuit model itself. Previous approaches to post-coupler stabilization are reviewed and the new, straightforward and accurate technique is described and demonstrated in the stabilization of the Linac4 DTL structures. PB - JACoW CP - Geneva, Switzerland SP - 547 EP - 550 KW - DTL KW - linac KW - cavity KW - drift-tube-linac KW - proton DA - 2017/05 PY - 2017 SN - 978-3-95450-169-4 DO - 10.18429/JACoW-LINAC2016-TUPLR038 UR - http://jacow.org/linac2016/papers/tuplr038.pdf ER -