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arXiv2020

Intra-bunch feedback system developments at DAFNE

This paper presents history and evolution of the intra-bunch feedback system for circular accelerators. This pro-ject has been presented by John D. Fox (SLAC/Stanford Un.) at the IPAC2010 held in Kyoto. The idea of the pro-posal is to build a flexible and powerful instrument to mit-igate the parasitic e-cloud effects on the proton (and poten-tially positron) beams in storage rings. Being a new and ambitious project, the financial issues have been quite im-portant. US LHC Accelerator Research Program (LARP) and other institution funding sources have assured the de-velopment of the design for implementing the feedback in the SPS ring at CERN. Here the intra-bunch feedback sys-tem has been installed and tested in the frame of the LIU (LHC Injector Upgrade) program. After the end of the LARP funding, a possible new inter-esting chance to continue the R&D activity, could be by implementing the system in a lepton storage ring affected by e-cloud effects. For achieving this goal, a possible ex-periment could be carried out in the positron ring of DAFNE at Frascati, Italy. The feasibility of the proposal is evaluated in the following sections. In case of approval of the experiment, indeed the project could be inserted in the DAFNE-TF (DAFNE Test Facility) program that is fore-seen after the 2020 for the following 3-5 years.

physics.acc-ph↗

arXiv2000

High Power Testing Results of the X-Band Mixed-Mode RF Windows for Linear Colliders

In this paper, we summarize the high power testing results of the X-band mixed-mode RF windows at KEK and SLAC for linear colliders. The main feature of these windows is that the combination of modes on the surface of the ceramic significantly decreases the electric and magnetic fields in the junction between the ceramic and the metal. So far two types of high power windows (with the diameter of 53 mm and 64 mm) have been fabricated. A high power model of the smaller type window was fabricated and tested in a resonant ring at KEK. A maximum circulating power of 81 MW with 300 ns duration or 66 MW with 700 ns duration was achieved. Light emission was observed for a power level of over 10 MW. Later, both windows were shipped to SLAC for even higher power testing using combined power from two klystrons. The first window (53 mm diameter) achieved a transmitted power of 80 MW with 1.5 microsec duration at 30 Hz repetition. It was not destroyed during the testing. The testing of the second window was carried out next to the small type and achieved 62 MW with 1.5 maicrosec duration with 10 Hz repetition. The final results of both windows are presented in this report.

hep-ex↗