S. Zhao, W. Chang, E. Daykin, E. Gutierrez, S.H. Kim, S.R. Kunjir, T.L. Larter, D.G. Morris, J.T. Popielarski
FRIB, East Lansing, Michigan, USA
Funding:Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The installation and commissioning of the FRIB superconducting linac adopts a phased strategy. In SRF’19 we reported the progress on the commissioning of the linear segment 1 (LS1) which contains mainly the quarter wave resonators (QWRs). In this paper, we will report the recent progress on the commissioning of the remainder of the linac, including linear segment 2 (LS2), folding segment 2 (FS2) and linear segment 3 (LS3), focusing on the RF system experience for the half wave resonators (HWRs). Compared to the QWRs, the HWRs have a different type of tuner, run at higher power levels and have additional components (for example, high voltage bias tee for multipacting suppression and spark detector). Topics such as nonlinear tuner control for the pneumatic tuners; auto turn on/off implementation; and early issues and failures will be discussed in more detail.
J. Plouin, E. Cenni, L. Maurice
CEA-DRF-IRFU, France
Studying flux expulsion during superconducting cavities test increases the need for exhaustive magnetometric cartography. The use of Anistropic Magneto Resistance (AMR) sensors, much cheaper than commercial fluxgates, allows the use of tens of sensors simultaneously. Such sensors are developed and sold for room temperature application but are resistant to cryogenic temperatures. However, they need proper calibration, which is more difficult at cryogenic temperature. Actually, this calibration uses the flip of the magnetization of the anisotropic ferromagnetic element, which coercitive field is increased at low temperature. We will present the development of method and software carried out at CEA for the use of such sensors, as well as the preliminary design of a rotating magnetometric device destined to elliptical cavities.
W. Xu, Z.A. Conway, J.M. Fite, D. Holmes, K.S. Smith, A. Zaltsman
BNL, Upton, New York, USA
Funding:This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The future EIC Electron storage ring at BNL needs to compensate up to 10 MW synchrotron loss with RF systems. The RF system relies on 34 fundamental power couplers to deliver RF power from power sources at room temperature to 17 SRF cavities at 2 K. Each power coupler will operate with 400 kW forward power, with full reflection for ~10% of time. We are developing two 1 MW coaxial FPCs at BNL, one with a BeO window and the other with an Al2O3 window. This paper will briefly summarize test results of high power test on the BeO window FPC , and then describe the development status of the Al2O3 window FPC.
M. Baudrier, G. Devanz, L. Maurice, O. Piquet
CEA-DRF-IRFU, France
For the development of efficient superconducting cavi-ties, field emission is an important parasitic phenomena to monitor. A diagnostic system composed of Geiger-Mueller (G-M) probes, NaI(Tl) scintillators are placed in the cryomodule test stand. Collected data is analysed and confronted to particle tracking simulation and electro magnetic shower code. With such systematic analysis we aim to identify the most probable field emission location and hence help to improve clean procedures during as-sembly and operation.
H.-W. Glock, J. Knobloch, A. Neumann, A. Veléz
HZB, Berlin, Germany
Industrial X-ray tomography offers the possibility to capture the entire inner and outer shape of an SRF cavity, providing also insights in weld quality and material defects. As a non-contact method this is especially attractive to investigate shape properties of fully processed and closed cavities. A drawback is the inherently strong X-ray damping of niobium, which causes the demand for intense hard X-rays, typically beyond the capabilities of dc-X-ray-tubes. This also limits the accuracy of material borders found by the tomographic inversion. To illustrate both capabilities and limitations, results of X-ray tomography investigations using three different cavities are reported, also describing the fundamental parameters and the hard- and software demands of the technology. We also discuss the non-trivial transferring of tomography data into RF simulation tools.
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