FRIB, East Lansing, Michigan, USA
Actuated diagnostics present additional challenges that static diagnostics devices do not such as alignment, stability, and incorporating an appropriate drive mechanism. These challenges become even more apparent as the actuaded length increases. At the Facility for Rare Isotope Beams (FRIB) we plan on using a number of actuated diagnostics devices including a Profile Monitor (AKA: Wire Scanner) with 12 inches of actuation. The Profile Monitor uses tungsten wires to traverse the beam pipe aperture to measure the beam intensity with respect to it’s location in the X-Y plane. This paper will detail the design of the 12 inch Profile Monitor and how it is able to overcome the stability, alignment, and drive issues that come with the 12 inches of actuation.
DESY, Hamburg, Germany
Fermilab, Batavia, Illinois, USA
CERN, Geneva, Switzerland
Transverse Higher Order Modes (HOM) excited by electron beams in the 3.9 GHz accelerating cavities at FLASH may damage the beam quality. They can be reduced by extracting their energy through special couplers and by aligning the beam in the cavity. Electronics has been designed at FNAL for monitoring some of the potentially most damaging HOMs. This may be used for beam centering and therefore reducing the HOM effects. Moreover, the signals can be potentially calibrated into beam offset, so that they could be used as beam position monitors (HOM-BPM). The specifications of the monitors have been defined during an extensive study on the 4-cavity accelerating module installed at FLASH. Signals around 5.44 GHz have been chosen for higher precision measurements. However these signals propagate into the entire 1.2 m long module. Therefore in addition modes at about 9 GHz were selected for localized measurements in each cavity. The electronics has been recently installed at FLASH. The commissioning results will be presented in this paper. Instabilities previously observed in a test electronics as well as the HOM-BPMs in 1.3 GHz cavities will also be investigated*. This electronics will also serve as a prototype for the electronics developed for the 3.9 GHz cavities at the European XFEL**.
*L. Shi et al., this Conference
**T. Wamsat et al., this Conference
KEK, Ibaraki, Japan
PSI, Villigen PSI, Switzerland
PSI, Villigen, Villigen, Switzerland
Wake field monitors (WFMs) are used to directly measure the alignment between beam and RF accelerating structure via the transverse higher mode spectrum. As a sub task of the EuCARD2 project, we are developing a front end for the monitors of the multipurpose X band structure installed at the SwissFEL Injector Test facility SITF at PSI. We plan to use electro optical technology offering strong advantages in the robustness to interference and radiation, and in the ease of signal transport. We present the concept of the device, discuss the theoretical performance in terms of noise. For a proof of principle, we built a basic system, which we tested together with the existing monitors with beam at SITF.
PSI, Villigen PSI, Switzerland
DESY, Hamburg, Germany
SwissFEL, the European XFEL (E-XFEL) and FLASH2 all use dual-resonator cavity beam position monitors (CBPMs). The CBPM electronics that is built by PSI has a larger number of calibration parameters that need to be determined in order to maximize the CBPM system performance. Beam measurements with the BPM electronics have been made in BPM test areas at the SwissFEL test injector and FLASH, as well as at FLASH2 where 17 E-XFEL type CBPMs have recently been installed in the undulator intersections [*,**]. The CBPMs are pre-calibrated in the lab using an automated test and calibration system [**], and then the final calibration is done with beam. This report discusses beam-based methods to optimize the system performance by improving the pre-beam system calibration as well as the mechanical alignment of the pickup position and angle.
* D. Lipka et al., "FLASH Undulator BPM Commissioning and Beam Characterization Results", IBIC'14
** M. Stadler et al., "Low-Q Cavity BPM Electronics for E-XFEL, FLASH-II and SwissFEL", IBIC'14