Related papers: Exploration of Parameters That Affect High Field Q…
Research linking surface hydrides to Q-disease, and the subsequent development of methods to eliminate surface hydrides, is one of the great successes of SRF cavity R&D. We use time-dependent Ginzburg-Landau to extend the theory of hydride…
Buffered Chemical Polishing (BCP) was the most conventional polishing method for superconducting radio frequency (SRF) Niobium (Nb) cavity surface preparation before the discovery of Electropolishing (EP), which is superior to BCP in high…
In this study, we present new insights on the origin of the high-field Q-slope in superconducting radio-frequency cavities. Consequent hydrofluoric acid rinses are used to probe the radio-frequency performance as a function of the material…
Many modern and proposed future particle accelerators rely on superconducting radio frequency cavities made of bulk niobium as primary particle accelerating structures. Such cavities suffer from the anomalous field dependence of their…
Even when cooled through its transition temperature in the presence of an external magnetic field, a superconductor can expel nearly all external magnetic flux. This Letter presents an experimental study to identify the parameters that most…
Superconducting niobium film cavities deposited on copper substrates (Nb/Cu) have suffered from strong field-dependent surface resistance, often referred to as the Q-slope problem, since their invention. We argue that the Q-slope may not be…
Main focus of this study is the investigation of thermodynamics phenomena responsible for the High Field Q Slope (HFQS) in SRF cavities by Internal Friction (IF) measurement. Mechanical spectroscopy is, indeed, a well-established technique…
We report the RF performance of several single-cell superconducting radio-frequency cavities subjected to low temperature heat treatment in nitrogen environment. The cavities were treated at temperature 120 - 165 $^{\circ}$C for an extended…
Q-slope issue, which is caused by the field dependent surface resistance, puzzled people for a long time in SRF fields. In this paper, we related the Q-slope with surface treatments; and proposed a surface-impurity model to explain the…
For many new accelerator applications, superconducting radio frequency (SRF) systems are the enabling technology. In particular for CW applications, much effort is being expended to minimize the power dissipation (surface resistance) of…
Niobium films are of interest in applications in various superconducting devices, such as superconducting radiofrequency cavities for particle accelerators and superconducting qubits for quantum computing. In this study, we addressed the…
In niobium superconducting radio frequency (SRF) accelerating cavities a decrease of the quality factor at lower fields - a so called \emph{low field Q slope or LFQS} - has been a long-standing unexplained effect. By extending the high $Q$…
High field Q-slope (HFQS) seriously limits the high gradient performance of the buffered chemically polished (BCP) superconducting radio frequency (SRF) niobium cavities. The direct cause or mechanism is not yet fully understood. In our…
The application of heat treatments on 1.3 GHz TESLA type cavities in ultra-high vacuum at 250{\deg}C to 350{\deg}C is called medium temperature or mid-T heat treatment. In various laboratories such treatments on superconducting radio…
We propose a model to explain power dissipation leading to the formation of hot spots in the inner walls of niobium thin film superconducting RF cavities. The physical mechanism that we explore is due to the constriction of surface…
Magnetic flux trapped during the cooldown of superconducting radio-frequency cavities through the transition temperature due to incomplete Meissner state is known to be a significant source of radio-frequency losses. The sensitivity of flux…
A model for the onset of the reduction in SRF cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Breakdown of the surface barrier against magnetic flux penetration at the cavity equator is…
The main source of RF losses leading to lower quality factor of superconducting radio-frequency cavities is due to the residual magnetic flux trapped during cool-down. The loss due to flux trapping is more pronounced for cavities subjected…
Previous studies on magnetic flux expulsion as a function of cooling details have been performed for superconducting niobium cavities with the cavity beam axis placed parallel respect to the helium cooling flow, and findings showed that for…
The effect of mid-T heat treatment on flux trapping sensitivity was measured on several 1.3 GHz single cell cavities subjected to vacuum annealing at temperature of 150 - 400 $^\circ$C for a duration of 3 hours. The cavity was cooldown with…