Carpenter, Adam
Data-Driven Gradient Optimization for Field Emission Management in a Superconducting Radio-Frequency Linac
Goldenberg, Steven, Ahammed, Kawser, Carpenter, Adam, Li, Jiang, Suleiman, Riad, Tennant, Chris
However, since the energy upgrade, CEBAF has suffered from significant FE induced radiation. With RF on, dose Jefferson Lab's Continuous Electron Beam Accelerator rates observed at 30 cm from the beamline are as high Facility (CEBAF) [1] relies on two superconducting as 10 rem/h and 100 rem/h for neutron and gamma radiation, radio-frequency linear accelerators (SRF linacs) to deliver respectively. This level of radiation causes significant high-energy electron beams to nuclear physics experiments damage to beamline components, including vacuum in the four experimental halls [2]. An integral valves, magnets, and cables of beam position monitors part of these linacs are cryomodules which contain and ion pumps. Replacing these components can use multiple SRF cavities. These SRF cavities provide the significant resources. Worse, portions of both linacs are main accelerating gradients to the electron beam, and considered "Radiation Areas" for days or even weeks into currently produce the 12 GeV beam necessary for scientific scheduled downtime, limiting maintenance activities to discovery.
Accelerating Cavity Fault Prediction Using Deep Learning at Jefferson Laboratory
Rahman, Monibor, Carpenter, Adam, Iftekharuddin, Khan, Tennant, Chris
Accelerating cavities are an integral part of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory. When any of the over 400 cavities in CEBAF experiences a fault, it disrupts beam delivery to experimental user halls. In this study, we propose the use of a deep learning model to predict slowly developing cavity faults. By utilizing pre-fault signals, we train a LSTM-CNN binary classifier to distinguish between radio-frequency (RF) signals during normal operation and RF signals indicative of impending faults. We optimize the model by adjusting the fault confidence threshold and implementing a multiple consecutive window criterion to identify fault events, ensuring a low false positive rate. Results obtained from analysis of a real dataset collected from the accelerating cavities simulating a deployed scenario demonstrate the model's ability to identify normal signals with 99.99% accuracy and correctly predict 80% of slowly developing faults. Notably, these achievements were achieved in the context of a highly imbalanced dataset, and fault predictions were made several hundred milliseconds before the onset of the fault. Anticipating faults enables preemptive measures to improve operational efficiency by preventing or mitigating their occurrence.
Anomaly Detection of Particle Orbit in Accelerator using LSTM Deep Learning Technology
Chen, Zhiyuan, Lu, Wei, Bhong, Radhika, Hu, Yimin, Freeman, Brian, Carpenter, Adam
A stable, reliable, and controllable orbit lock system is crucial to an electron (or ion) accelerator because the beam orbit and beam energy instability strongly affect the quality of the beam delivered to experimental halls. Currently, when the orbit lock system fails operators must manually intervene. This paper develops a Machine Learning based fault detection methodology to identify orbit lock anomalies and notify accelerator operations staff of the off-normal behavior. Our method is unsupervised, so it does not require labeled data. It uses Long-Short Memory Networks (LSTM) Auto Encoder to capture normal patterns and predict future values of monitoring sensors in the orbit lock system. Anomalies are detected when the prediction error exceeds a threshold. We conducted experiments using monitoring data from Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF). The results are promising: the percentage of real anomalies identified by our solution is 68.6%-89.3% using monitoring data of a single component in the orbit lock control system. The accuracy can be as high as 82%.