Development and integration of DAQ system for beam current monitoring of the KOMAC linac and beamlines

Abstract

The KOMAC has mainly used commercial oscilloscopes for beam current monitoring (BCM). The beam current is measured with an oscilloscope and the measured signal values are collected using Ethernet. At this process, Experimental Physics and Industrial Control System (EPICS) converts the raw voltage values into beam current and transmits each data to users via Channel Access (CA). The beam waveform is remotely shared by utilizing virtual network computing (VNC) to access the oscilloscope’s graphic desktop. The process variables (PV) of beam currents can be monitored and stored simultaneously, and data analysis is possible at any time using an API. However, as the accelerator duty cycle improves, synchronization becomes necessary for beam data collection, and it has been confirmed that there are occurrences of missing the PV of the beam current. This issue has two main causes. Firstly, data collection operates in a polling method within TCP/IP communication. The advantage of polling is that its implementation is relatively straightforward. Since the client periodically sends requests, the communication system can predict when data will be received, reducing overhead. On the other side, a drawback is that no updates occur until data are requested, resulting in lower real-time capability. Therefore, without synchronization with the timing system, accurate collection of pulsed beam data becomes challenging. Secondly, as the beam duty increases, a considerable amount of beam data is missing due to transmission limits. To address this, a Data Acquisition (DAQ) for beam current acquisition has been developed, and testing and debugging have been completed. This paper describes the design, debugging, and operational plans of beam current monitoring system.