Author: Dhakal, P.
Paper Title Page
SUPTEV010 Electrical and Thermal Properties of Cold-Sprayed Bulk Copper and Copper-Tungsten Samples at Cryogenic Temperatures 142
 
  • H. Pokhrel
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, P. Dhakal, J.K. Spradlin
    JLab, Newport News, Virginia, USA
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, Solon, Ohio, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, SBIR grant DE-SC00195589
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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV010  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 15 November 2021 — Issue date ※ 21 March 2022
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MOPCAV005 Status of SNS Proton Power Upgrade SRF Cavities Production Qualification 265
 
  • P. Dhakal, E. Daly, G.K. Davis, J.F. Fischer, D. Forehand, N.A. Huque, A.L.A. Mitchell, P.D. Owen
    JLab, Newport News, Virginia, USA
  • M.P. Howell, S.-H. Kim, J.D. Mammosser
    ORNL, Oak Ridge, Tennessee, USA
 
  The Proton Power Upgrade project at Oak Ridge National Lab’s Spallation Neutron Source (SNS PPU) currently being constructed will double the proton beam power from 1.4 to 2.8 MW by adding 7 additional cryomodules, each contains four six-cell high beta (\beta = 0.81) superconducting radio frequency cavities. The cavities were built by Research Instruments, Germany, with all the cavity processing done at the vendor site, including electropolishing as the final active chemistry step. All 28 cavities needed for 7 cryomodules were delivered to Jefferson Lab, ready to be tested. The cryogenic RF qualifications and helium vessel welding were done at Jefferson Lab. The performance largely exceed the requirements, and greatly exceeded the performance of the original SNS cavity production series. Here, we present the summary of RF test on production cavities to this date.
This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
 
poster icon Poster MOPCAV005 [1.061 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV005  
About • Received ※ 19 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 12 March 2022 — Issue date ※ 06 April 2022
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MOPFDV008 SRF Levitation and Trapping of Nanoparticles 331
 
  • R.L. Geng
    ORNL, Oak Ridge, Tennessee, USA
  • P. Dhakal, B.J. Kross, F. Marhauser, J.E. McKisson, J. Musson, H. Wang, A. Weisenberger, W.Z. Xi
    JLab, Newport News, Virginia, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences & Office of Nuclear Physics.
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.
 
poster icon Poster MOPFDV008 [0.595 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV008  
About • Received ※ 10 June 2021 — Accepted ※ 30 September 2021 — Issue date; ※ 02 May 2022  
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WEPFDV008 Thermal Conductivity of Electroplated Copper Onto Bulk Niobium at Cryogenic Temperatures 576
 
  • G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  • I.P. Parajuli, M.R.P. Walive Pathiranage
    ODU, Norfolk, Virginia, USA
  • T. Saeki
    KEK, Ibaraki, Japan
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV008  
About • Received ※ 17 June 2021 — Accepted ※ 10 September 2021 — Issue date; ※ 01 March 2022  
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THPCAV008 Results From the Proton Power Upgrade Project Cavity Quality Assurance Plan 801
 
  • J.D. Mammosser, E. Robertson
    ORNL RAD, Oak Ridge, Tennessee, USA
  • R. Afanador, M.S. Champion, M.N. Greenwood, M.P. Howell, S.-H. Kim, S.E. Stewart, D.J. Vandygriff
    ORNL, Oak Ridge, Tennessee, USA
  • A. Bitter, K.B. Bolz, A. Navitski, L. Zweibaeumer
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • E. Daly, G.K. Davis, P. Dhakal, D. Forehand, K. Macha, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  Funding: UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE)
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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV008  
About • Received ※ 04 June 2021 — Accepted ※ 06 September 2021 — Issue date; ※ 16 May 2022  
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FROFDV02
A Novel Approach to Producing High Gradient and Q0 Cavities in Non-Ideal Furnaces  
 
  • A.D. Palczewski, P. Dhakal, C.E. Reece
    JLab, Newport News, Virginia, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
 
  Funding: Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
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.
 
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