ODU, Norfolk, Virginia, USA
JLab, Newport News, Virginia, USA
Euclid TechLabs, Solon, Ohio, USA
The development of high thermal conductivity coatings with pure copper or copper-tungsten alloy could be beneficial to improve the heat transfer of bulk Nb cavities for conduction cooling applications and to increase the stiffness of bulk Nb cavities cooled by liquid helium. Cold-spray is an additive manufacturing technique suitable to grow thick coatings of either Cu or CuW on a Nb substrate. Bulk (~5 mm thick) coatings of Cu and CuW were deposited on standard 3 mm thick, high-purity Nb samples and smaller samples with 2 mm x 2 mm cross section were cut for measuring the thermal conductivity and the residual resistivity ratio. The samples were subjected to annealing at different temperatures and a maximum RRR of ~130 and ~40 were measured for the Cu samples and CuW samples, respectively.
JLab, Newport News, Virginia, USA
ORNL, Oak Ridge, Tennessee, USA
This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
ORNL, Oak Ridge, Tennessee, USA
JLab, Newport News, Virginia, USA
A proposal has been conceived to levitate and trap mesoscopic particles using radio frequency (RF) fields in a superconducting RF(SRF) cavity. Exploiting the intrinsic characteristics of an SRF cavity, this proposal aims at overcoming a major limit faced by state-of-the-art laser trapping techniques. The goal of the proposal is to establish a foundation to enable observation of quantum phenomena of an isolated mechanical oscillator interacting with microwave fields. An experiment supported by LDRD funding at JLab has started to address R&D issues relevant to these new research directions using existing SRF facilities at JLab. The success of this experiment would establish its groundbreaking relevance to quantum information science and technology, which may lead to applications in precision force measurement sensors, quantum memories, and alternative quantum computing implementations with promises for superior coherence characteristics and scalability well beyond the start-of-the-art. In this contribution, we will introduce the proposal and basic consideration of the experiment.
JLab, Newport News, Virginia, USA
ODU, Norfolk, Virginia, USA
KEK, Ibaraki, Japan
Superconducting radio-frequency (SRF) cavities made of high-purity bulk niobium are widely used in modern particle accelerators. The development of metallic outer coatings with high thermal conductivity would have a beneficial impact in terms of improved thermal stability, reduced material cost and for the development of conduction-cooled, cryogenic-free SRF cavities. Several high-purity, fine-grain Nb samples have been coated with 2’4 mm thick copper by electroplating. Measurements of the thermal conductivity of the bimetallic Nb/Cu samples in the range 2’7 K showed values of the order of 1 kW/(m K) at 4.3 K. Very good adhesion between copper and niobium was achieved by depositing a thin Cu layer by cold spray on the niobium, prior to electroplating the bulk Cu layer.
ORNL RAD, Oak Ridge, Tennessee, USA
ORNL, Oak Ridge, Tennessee, USA
RI Research Instruments GmbH, Bergisch Gladbach, Germany
JLab, Newport News, Virginia, USA
The Proton Power Upgrade (PPU) Project at Oak Ridge National Lab’s Spallation Neutron Source (SNS) is currently under construction. The project will double the beam power from 1.4 to 2.8 MW. This is accomplished by increasing the beam current and adding seven new Superconducting Radio Frequency (SRF) cryomodules. Each new cryomodule will contain four six-cell, beta 0.81, PPU style cavities. A quality assurance plan was developed and implemented for the procurement of 32 PPU cavities. As part of this plan, reference cavities were qualified and sent to Research Instruments Co. for the development and verification of process steps. Here we present the results from this plan to date.
FROFDV02
JLab, Newport News, Virginia, USA
SLAC, Menlo Park, California, USA
Since the discovery of nitrogen doping in 2014, infusion in 2017, "mid-T bakes in 2018; the reproducibility in both Q0 and gradient has been proven to be highly variable between facilities and even within the same furnace within a facility*. Multiple studies have pointed to possible contamination from pumps, non-Molybdenum frame outgassing within a hot zone, gas purity issues, and cross-contamination between furnace runs. The traditional approach to mitigating these effects is using niobium furnace caps, high-temperature furnace burnout runs, and expensive pump replacements. We will show multiple examples of a novel approach to increasing Q0 and Q0+Eacc, using a simple treatment after a furnace treatment or doping + light EP. We will also outline the possible workflows using this new technique in production.
*Pashupati Dhakal, https://doi.org/10.1016/j.physo.2020.100034, and enclosed citations.