Superconducting RF Cavity Frequency and Field Distribution Sensitivity Simulation
Frequency and electromagnetic field distribution sensitivity of a superconducting RF (SRF) cavity are the fundamental phyical paramethers in cavity and tuner design. At low temperature, the frequency sensitivity can be obtained by measuring prototype cavity, but it is not easy to test the filed distribution sensitivity. This paper presents and describes a simulation method combining ANSYS and SUPERFISH to calculate the cavity frequency and field distribution variation due to cavity’s small deformation caused by mechanical force, radiation force, thermal expansion etc.. As an example, the simulation results of the frequency and field flatness sensitivity on the SNS cavities were confirmed by their test results.
EFFECT OF THE TUNER ON THE FIELD FLATNESS OF SNS SUPERCONDUCTING RF CAVITIES
The field flatness (FF) in a multi-cell superconducting cavity affects not only net accelerating voltage, but also peak surface field [1] and Lorentz detuning coefficient [2]. Our measurements indicate that the tuner’s motion changes not only the cavity frequency but also its FF. This field amplitude change is a linear tilt and proportional to the distance between each cell center and the cavity’s geometric center. This tilt also changes the coupling of the Fundamental Power Coupler (FPC) and Field Probe (FP) on either side of the cavity. The tilt has been measured and simulated, and is ~20%/MHz on the Spallation Neutron Source (SNS) medium β cavities. The FF change is not only due to the uneven volume change within the cell, but also due to the cell-to-cell coupling.
Strategies for glass based photonic system integration
There is a clear tendency to integrate more and more opto-electronic and micro-optical components like optical fibers, laser diodes, modulators, isolators, beam-splitting components and micro lenses in also increasingly dense and complex assemblies. The paper will discuss thin glass as a very promising base material for that kind of photonic packaging on interposer and board level including optical interconnection using fibers.