245 citations · 700 across the 19 of their papers we have counts for
20 papers
Accelerating fields up to 49 MV/m in TESLA-shape superconducting RF niobium cavities via 75C vacuum bake
A. Grassellino, A. Romanenko, D. Bice +9
In this paper we present the discovery of a new surface treatment applied to superconducting radio frequency (SRF) niobium cavities, leading to unprecedented accelerating fields of…
The Effect of Mechanical Cold Work on the Magnetic Flux Expulsion of Niobium
S. Posen, S. K. Chandrasekaran, A. C. Crawford +5
Expulsion of ambient flux has been shown to be crucial to obtain high quality factors in bulk niobium SRF cavities. However, there remain many questions as to what properties of th…
Cryomodule Test Stand Reduced-Magnetic Support Design At Fermilab
M. W. McGee, S. K. Chandrasekaran, A. C. Crawford +3
In a partnership with SLAC National Accelerator Laboratory (SLAC) and Jefferson Lab, Fermilab will assemble and test 17 of the 35 total 1.3 GHz cryomodules for the Linac Coherent L…
Unprecedented Quality Factors at Accelerating Gradients up to 45 MV/m in Niobium Superconducting Resonators via Low Temperature Nitrogen Infusion
A. Grassellino, A. Romanenko, Y. Trenikhina +9
We report the finding of new surface treatments that permit to manipulate the niobium resonator nitrogen content in the first few nanometers in a controlled way, and the resonator…
Extreme diffusion limited electropolishing of niobium radiofrequency cavities
Anthony C. Crawford
A deeply modulated, regular, continuous, oscillating current waveform is reliably and repeatably achieved during electropolishing of niobium single-cell elliptical radiofrequency c…
Demagnetization of a Complete Superconducting Radiofrequency Cryomodule: Theory and Practice
Anthony C. Crawford, Saravan K. Chandrasekaran
A significant advance in magnetic field management in a fully assembled superconducting radiofrequency cryomodule has been achieved and is reported here. Demagnetization of the ent…
Mechanically Stimulated Domain Re-arrangement in Cryogenic Magnetic Shielding Materials
Anthony C. Crawford
Room temperature properties and behavior of several types of cryogenic magnetic shielding materials are measured and reported here. Large changes in the effective relative permeabi…
Observation of Magnetic Superviscosity in Metglas 2605SA1
Anthony C. Crawford
A quasi time constant for magnetic domain relaxation of Metglas 20605SA1 has been measured to be 2.6 hours. The effective relative magnetic permeability has been measured to be 57,…
Hydrogen in the LCLS2 Beamline Vacuum
Anthony C. Crawford
This note demonstrates that the cold segments of the LCLS2 linac will cryopump hydrogen for long periods of time, mitigating concerns for beam-residual gas interactions.
Modeling of Mechanical Overlap Joints in Magnetic Shields
Anthony C. Crawford
This study determines a useful value to use for the gap width of mechanical overlap joints in models of magnetic shielding. The average value of 0.1 mm is found to agree with measu…
Efficient expulsion of magnetic flux in superconducting RF cavities for high applications
S. Posen, A. Grassellino, A. Romanenko +5
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 present…
In Situ Cryomodule Demagnetization
Anthony C. Crawford
The feasibility of in-situ demagnetization of fully assembled superconducting RF cryomodules is demonstrated. Useful parametric values for demagnetization as well as measured effec…
Cooling Dynamics Through Transition Temperature of Niobium SRF Cavities Captured by Temperature Mapping
M. Martinello, A. Romanenko, M. Checchin +4
Cool-down dynamics of superconducting accelerating cavities became particularly important for obtaining very high quality factors in SRF cavities. Previous studies proved that when…
Superconducting RF Cryomodule Demagnetization
Anthony C. Crawford
This note presents measurements that support the proposition that it is feasible to demagnetize a fully assembled superconducting RF cryomodule.
Magnetic Flux Dynamics in Horizontally Cooled Superconducting Cavities
M. Martinello, M. Checchin, A. Grassellino +4
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 resp…
Ultra-high quality factors in superconducting niobium cavities in ambient magnetic fields up to 190 mG
A. Romanenko, A. Grassellino, A. C. Crawford +2
Ambient magnetic field, if trapped in the penetration depth, leads to the residual resistance and therefore sets the limit for the achievable quality factors in superconducting nio…
A Study of Magnetic Shielding Performance of a Fermilab International Linear Collider Superconducting RF Cavity Cryomodule
Anthony C. Crawford
This note presents measurements that support the conclusion that it is feasible to achieve magnetic field values at the level of 5 milliGauss for a cryomodule in a realistic and re…
A Study of Thermocurrent Induced Magnetic Fields in ILC Cavities
Anthony C. Crawford
The case of axisymmetric ILC type cavities with titanium helium vessels is investigated. A first order estimate for magnetic field within the SRF current layer is presented. The in…
Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures
A. Grassellino, A. Romanenko, O. Melnychuk +7
We report a surface treatment that systematically improves the quality factor of niobium radio frequency cavities beyond the expected limit for niobium. A combination of annealing…
Fermilab experience of post-annealing losses in SRF niobium cavities due to furnace contamination and the ways to its mitigation: a pathway to processing simplification and quality factor improvement
A. Grassellino, A. Romanenko, A. Crawford +10
We investigate the effect of high temperature treatments followed by only high-pressure water rinse (HPR) of superconducting radio frequency (SRF) niobium cavities. The objective i…