Abstract:
This paper presents a project done in collaboration with Brookhaven National
Lab for the application of Radio Frequency Beam Position Monitors (BPM). These
Radio Frequency Beam Position Monitors are to be used in the particle accelerator
facility (NSLS-II) post construction. The purpose of the RF BPM is to detect
transverse beam position with sub-micron resolution and stability for normal
operation conditions. The most crucial parameter of the BPM to accurately measure
the position is for the gains of the four channels to be matched. Traditional
calibration schemes comprise of manually adjusting a signal generator coupled
to the RF BPM unit under test and recording the receiver signal strength for
various power level settings. A MATLAB “RF BPM Cal Tool” has been
developed to automate the process. The tool controls the signal generator and
communicates with the BPM unit, both over TCP/IP, and was developed utilizing
the MathWorks Instrument Control Toolbox. Remote control of the signal generator
is executed using the VISA-TCP protocol in conjunction with SCPI commands. Communication
with the BPM is established using the ModBus-TCP protocol and the raw data is
read and handled by the Cal Tool. A created graphical user interface implements
the aforementioned functionality. A final post-processing step is implemented
in the GUI and exports the calculated systematic gain coefficients to a user-specified
filed to be used for further verification. Testing of the tool proved successful,
although a ModBus-TCP Slave program was used to simulate the yet-to-be-completed
BPM unit under test. Further testing will be required once the final hardware
is completed.
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