superconducting radio frequency
Recently Published Documents


TOTAL DOCUMENTS

204
(FIVE YEARS 53)

H-INDEX

14
(FIVE YEARS 3)

2022 ◽  
Vol 12 (2) ◽  
pp. 546
Author(s):  
Peng Sha ◽  
Weimin Pan ◽  
Jiyuan Zhai ◽  
Zhenghui Mi ◽  
Song Jin ◽  
...  

Medium-temperature (mid-T) furnace baking was conducted at 650 MHz superconducting radio-frequency (SRF) cavity for circular electron positron collider (CEPC), which enhanced the cavity unloaded quality factor (Q0) significantly. In the vertical test (2.0 K), Q0 of 650 MHz cavity reached 6.4 × 1010 at 30 MV/m, which is remarkably high at this unexplored frequency. Additionally, the cavity quenched at 31.2 MV/m finally. There was no anti-Q-slope behavior after mid-T furnace baking, which is characteristic of 1.3 GHz cavities. The microwave surface resistance (RS) was also studied, which indicated both very low Bardeen–Cooper–Schrieffer (BCS) and residual resistance. The recipe of cavity process in this paper is simplified and easy to duplicate, which may benefit the SRF community.


2022 ◽  
Vol 4 ◽  
Author(s):  
Lasitha Vidyaratne ◽  
Adam Carpenter ◽  
Tom Powers ◽  
Chris Tennant ◽  
Khan M. Iftekharuddin ◽  
...  

This work investigates the efficacy of deep learning (DL) for classifying C100 superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. CEBAF is a large, high-power continuous wave recirculating linac that utilizes 418 SRF cavities to accelerate electrons up to 12 GeV. Recent upgrades to CEBAF include installation of 11 new cryomodules (88 cavities) equipped with a low-level RF system that records RF time-series data from each cavity at the onset of an RF failure. Typically, subject matter experts (SME) analyze this data to determine the fault type and identify the cavity of origin. This information is subsequently utilized to identify failure trends and to implement corrective measures on the offending cavity. Manual inspection of large-scale, time-series data, generated by frequent system failures is tedious and time consuming, and thereby motivates the use of machine learning (ML) to automate the task. This study extends work on a previously developed system based on traditional ML methods (Tennant and Carpenter and Powers and Shabalina Solopova and Vidyaratne and Iftekharuddin, Phys. Rev. Accel. Beams, 2020, 23, 114601), and investigates the effectiveness of deep learning approaches. The transition to a DL model is driven by the goal of developing a system with sufficiently fast inference that it could be used to predict a fault event and take actionable information before the onset (on the order of a few hundred milliseconds). Because features are learned, rather than explicitly computed, DL offers a potential advantage over traditional ML. Specifically, two seminal DL architecture types are explored: deep recurrent neural networks (RNN) and deep convolutional neural networks (CNN). We provide a detailed analysis on the performance of individual models using an RF waveform dataset built from past operational runs of CEBAF. In particular, the performance of RNN models incorporating long short-term memory (LSTM) are analyzed along with the CNN performance. Furthermore, comparing these DL models with a state-of-the-art fault ML model shows that DL architectures obtain similar performance for cavity identification, do not perform quite as well for fault classification, but provide an advantage in inference speed.


2021 ◽  
Vol 119 (19) ◽  
pp. 194102
Author(s):  
A. Dangwal Pandey ◽  
T. F. Keller ◽  
M. Wenskat ◽  
A. Jeromin ◽  
S. Kulkarni ◽  
...  

2021 ◽  
Author(s):  
Daniel Andrew Turner ◽  
Graeme Burt ◽  
Tobias Junginger

Abstract Superconducting Radio-Frequency cavities are currently made out of niobium. Niobium cavities are limited by the magnetic field on the cavity walls due to the entry of vortices at the field of first vortex penetration, Hvp. Low temperature baking in vacuum or low pressure gas atmosphere removes the strong decrease of the quality factor with accelerating gradient (high field Q-slope). Some cavities reach surface magnetic field above the lower critical field, Hc1. One hypothesis for this performance increase is that the outer layer affected by the treatments acts as a barrier for vortex penetration (effective bilayer). Using a vibrating sample magnetometer the field of first flux penetration (Hvp) was measured for Nb ellipsoids with various low temperature treatments. All Hvp values were found to be consistent with the lower critical field, Hc1 , as predicted for clean niobium. This led to the conclusion that a metastable flux free state above Hc1 cannot be observed in DC magnetometry for low temperature baked niobium unlike for bilayers consisting of two superconductors as previously published. The effect of flux pinning differed significantly between treatments, suggesting that the high field Q-slope mitigation might be related to vortex pinning in the surface of the cavities.


2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Marco Gorghetto ◽  
Gilad Perez ◽  
Inbar Savoray ◽  
Yotam Soreq

Abstract In this paper we study CP violation in photon self-interactions at low energy. These interactions, mediated by the effective operator $$ FFF\tilde{F} $$ FFF F ˜ , where ($$ \tilde{F} $$ F ˜ ) F is the (dual) electromagnetic field strength, have yet to be directly probed experimentally. Possible sources for such interactions are weakly coupled light scalars with both scalar and pseudoscalar couplings to photons (for instance, complex Higgs-portal scalars or the relaxion), or new light fermions coupled to photons via dipole operators. We propose a method to isolate the CP-violating contribution to the photon self-interactions using Superconducting Radio-Frequency cavities and vacuum birefringence experiments. In addition, we consider several theoretical and experimental indirect bounds on the scale of new physics associated with the above effective operator, and present projections for the sensitivity of the proposed experiments to this scale. We also discuss the implications of these bounds on the CP-violating couplings of new light particles coupled to photons.


Scilight ◽  
2021 ◽  
Vol 2021 (34) ◽  
pp. 341106
Author(s):  
Jaimee-Ian Rodriguez

2021 ◽  
Vol 92 (8) ◽  
pp. 083203
Author(s):  
J. Stark ◽  
C. Warnecke ◽  
S. Bogen ◽  
S. Chen ◽  
E. A. Dijck ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document