SRF2017 - List of Authors (Tan, W.W.)

Paper	Title	Page
MOPB036	The Study of Deposition Method of Nb3Sn Film on Cu Substrate	131
	L. Xiao, X.Y. Lu, W.W. Tan, D. Xie, D.Y. Yang, Y. Yang, Z.Q. Yang, J. Zhao PKU, Beijing, People's Republic of China
	Our work is mainly focused on the fabrication methods of Nb3Sn films on Cu substrates and film's properties. There are diffraction peaks of Nb3Sn in the X-ray diffraction patterns in which without diffraction peaks of copper compounds. Scanning electron microstructures of Nb3Sn film reflect its nice compactness and binding force between film and substrate.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB036
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MOPB082	A Preliminary Scheme for X-ray Emission Based on Micro-pulse Electron Gun	259
	Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D.Y. Yang, Z.Q. Yang, J. Zhao PKU, Beijing, People's Republic of China
	X-ray is now widely used in many areas of physics, biology, chemistry and materials. And how to achieve emission, monochrome, and focusing of x-ray is of great significance to study. Micro-pulse electron gun (MPG) is a new type of electron source, with characteristics of high repetition frequency, short-pulse and low cost. Generating x-ray with better monochromaticity is one of the potential applications of MPG. And a preliminary scheme of X-ray based on MPG is proposed in this paper. The scheme is designed by comparing different anode materials and the thickness of filters. The simulation results based on the software MCNP5 show that the proposed scheme can effectively improve the monotonicity of the generated X-rays.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB082
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TUXBA03	N-H Interaction Study of Nitrogen Doping-treatment on Nb Samples
	Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao PKU, Beijing, People's Republic of China
	Fundamental understanding of the nitrogen doping mechanism has been carried out extensively, but yet remains unclear. We studied the nitrogen doping effect through a series of experiments on niobium samples at both room and low temperature circumstances to seek the physical explanation based on the proposed nitrogen-hydrogen interaction. The time of flight secondary ion mass spectrometry (TOF-SIMS) revealed that the diffused nitrogen plays a key role in the nitrogen doping effect. X-ray photoelectron spectroscopy (XPS) measurements showed the chemical distribution of it. The effects of different concentrations of diffused nitrogen on the samples' magnetic property were studied by the magnetic property measurement system (MPMS). Direct observation of the surface topography of both doped and undoped samples by using scanning electron microscope (SEM) at liquid nitrogen temperature has proved that the diffused nitrogen can prevent or retard the hydrides formation to varying degrees with different amounts of material removal. A possible mechanism of nitrogen-doping effect is proposed based on our study.
	Slides TUXBA03 [3.235 MB]
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TUPB055	Nb3Sn Thin Film Deposition On Copper By DC Magnetron Sputtering	512
	W.W. Tan, B.T. Li, X.Y. Lu, L. Xiao, D. Xie, D.Y. Yang, Y. Yang, Z.Q. Yang, J. Zhao PKU, Beijing, People's Republic of China
	Nb3Sn for SRF cavities has been coated on copper samples by DC magnetron Sputtering. Pure Nb target and pure Sn target were installed separately in the magnetron sputtering device. Nb3Sn precursor was coated on copper in the Ar atmosphere of 0.5 Pa. The Nb3Sn precursor was annealed in the vacuum furnace whose pressure is 10^-4 Pa. The XRD results demonstrate the exist of Nb3Sn crystal, and MPMS results show superconductivity of Nb3Sn. The highest critical temperature obtained is 15K.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB055
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THPB029	XPS Studies of Nitrogen Doping Nb Samples before and after GCIB Etching	802
	Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao PKU, Beijing, People's Republic of China
	The surface chemical composition of nitrogen doping Nb samples used for the fabrication of superconducting radio frequency (SRF) cavities, followed by the subsequent successive EP with different amounts of material removal, has been studied by XPS. The chemical composition of Nb, O, C and N was presented before and after Gas Cluster Ion Beams (GCIB) etching. No signals of bad superconducting nitrides NbNx was found in any doped and un-doped samples before etching. However, in the depth range greater than 30nm, the content of N elements is below the XPS detection precision scope even in the samples directly after nitrogen doping treatment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB029
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THPB030	Direct Observation of Hydrides Formation of Nitrogen Doping Nb Samples	805
	Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao PKU, Beijing, People's Republic of China
	Direct observation of hydrides precipitates formation on both nitrogen doped and un-doped Nb samples at 80K has been carried out using Scanning Electron Microscope (SEM) with Cold Stand. We have found that, under our experimental conditions, when the subsequent EP removal is less than 7μm, the amounts of hydrides formed on the surface of doped samples can be effectively reduced. When the subsequent material removal is larger than 9μm, the amounts of precipitated hydrides increased with the EP removal. When the EP removal is 7-9μm, the amounts of hydrides can still be effectively reduced. Also, more hydrides were precipitated on the surface of un-doped samples. The amounts of hydrides of doped samples may be reduced to varying degrees with different amounts of material removal.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB030
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THPB031	Magnetic Properties of Nitrogen Doping Niobium Samples	809
	Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao PKU, Beijing, People's Republic of China
	Nitrogen doping study on Niobium samples used for the fabrication of superconducting radio frequency (SRF) cavities was carried out. The samples' surface treatments were attempted to replicate that of the cavities, which included heavy electropolishing (EP), nitrogen doping and the subsequent successive EP with different amounts of material removal. The magnetization curves of both doped and un-doped samples have been measured, from which the lower critical field Hffp (First Flux Penetration, ffp) and upper critical field Hc2 was extracted. The thermodynamic critical field Hc, superheating field Hsh and superconducting parameters of samples with different treatments was calculated from the determined reversible magnetization curves. Hsh of doped samples is obviously smaller than that of un-doped samples, which may be a possible reason for the reduction of achievable accelerating gradient in SRF niobium cavities after nitrogen doping treatments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB031
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Paper

Title

Page

The Study of Deposition Method of Nb3Sn Film on Cu Substrate

131

L. Xiao, X.Y. Lu, W.W. Tan, D. Xie, D.Y. Yang, Y. Yang, Z.Q. Yang, J. Zhao
PKU, Beijing, People's Republic of China

Our work is mainly focused on the fabrication methods of Nb3Sn films on Cu substrates and film's properties. There are diffraction peaks of Nb3Sn in the X-ray diffraction patterns in which without diffraction peaks of copper compounds. Scanning electron microstructures of Nb3Sn film reflect its nice compactness and binding force between film and substrate.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPB082

A Preliminary Scheme for X-ray Emission Based on Micro-pulse Electron Gun

259

Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D.Y. Yang, Z.Q. Yang, J. Zhao
PKU, Beijing, People's Republic of China

X-ray is now widely used in many areas of physics, biology, chemistry and materials. And how to achieve emission, monochrome, and focusing of x-ray is of great significance to study. Micro-pulse electron gun (MPG) is a new type of electron source, with characteristics of high repetition frequency, short-pulse and low cost. Generating x-ray with better monochromaticity is one of the potential applications of MPG. And a preliminary scheme of X-ray based on MPG is proposed in this paper. The scheme is designed by comparing different anode materials and the thickness of filters. The simulation results based on the software MCNP5 show that the proposed scheme can effectively improve the monotonicity of the generated X-rays.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB082

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXBA03

N-H Interaction Study of Nitrogen Doping-treatment on Nb Samples

Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao
PKU, Beijing, People's Republic of China

Fundamental understanding of the nitrogen doping mechanism has been carried out extensively, but yet remains unclear. We studied the nitrogen doping effect through a series of experiments on niobium samples at both room and low temperature circumstances to seek the physical explanation based on the proposed nitrogen-hydrogen interaction. The time of flight secondary ion mass spectrometry (TOF-SIMS) revealed that the diffused nitrogen plays a key role in the nitrogen doping effect. X-ray photoelectron spectroscopy (XPS) measurements showed the chemical distribution of it. The effects of different concentrations of diffused nitrogen on the samples' magnetic property were studied by the magnetic property measurement system (MPMS). Direct observation of the surface topography of both doped and undoped samples by using scanning electron microscope (SEM) at liquid nitrogen temperature has proved that the diffused nitrogen can prevent or retard the hydrides formation to varying degrees with different amounts of material removal. A possible mechanism of nitrogen-doping effect is proposed based on our study.

Slides TUXBA03 [3.235 MB]

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB055

Nb3Sn Thin Film Deposition On Copper By DC Magnetron Sputtering

512

W.W. Tan, B.T. Li, X.Y. Lu, L. Xiao, D. Xie, D.Y. Yang, Y. Yang, Z.Q. Yang, J. Zhao
PKU, Beijing, People's Republic of China

Nb3Sn for SRF cavities has been coated on copper samples by DC magnetron Sputtering. Pure Nb target and pure Sn target were installed separately in the magnetron sputtering device. Nb3Sn precursor was coated on copper in the Ar atmosphere of 0.5 Pa. The Nb3Sn precursor was annealed in the vacuum furnace whose pressure is 10^-4 Pa. The XRD results demonstrate the exist of Nb3Sn crystal, and MPMS results show superconductivity of Nb3Sn. The highest critical temperature obtained is 15K.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPB029

XPS Studies of Nitrogen Doping Nb Samples before and after GCIB Etching

802

Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao
PKU, Beijing, People's Republic of China

The surface chemical composition of nitrogen doping Nb samples used for the fabrication of superconducting radio frequency (SRF) cavities, followed by the subsequent successive EP with different amounts of material removal, has been studied by XPS. The chemical composition of Nb, O, C and N was presented before and after Gas Cluster Ion Beams (GCIB) etching. No signals of bad superconducting nitrides NbNx was found in any doped and un-doped samples before etching. However, in the depth range greater than 30nm, the content of N elements is below the XPS detection precision scope even in the samples directly after nitrogen doping treatment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB029

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPB030

Direct Observation of Hydrides Formation of Nitrogen Doping Nb Samples

805

Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao
PKU, Beijing, People's Republic of China

Direct observation of hydrides precipitates formation on both nitrogen doped and un-doped Nb samples at 80K has been carried out using Scanning Electron Microscope (SEM) with Cold Stand. We have found that, under our experimental conditions, when the subsequent EP removal is less than 7μm, the amounts of hydrides formed on the surface of doped samples can be effectively reduced. When the subsequent material removal is larger than 9μm, the amounts of precipitated hydrides increased with the EP removal. When the EP removal is 7-9μm, the amounts of hydrides can still be effectively reduced. Also, more hydrides were precipitated on the surface of un-doped samples. The amounts of hydrides of doped samples may be reduced to varying degrees with different amounts of material removal.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPB031

Magnetic Properties of Nitrogen Doping Niobium Samples

809

Z.Q. Yang, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, J. Zhao
PKU, Beijing, People's Republic of China

Nitrogen doping study on Niobium samples used for the fabrication of superconducting radio frequency (SRF) cavities was carried out. The samples' surface treatments were attempted to replicate that of the cavities, which included heavy electropolishing (EP), nitrogen doping and the subsequent successive EP with different amounts of material removal. The magnetization curves of both doped and un-doped samples have been measured, from which the lower critical field Hffp (First Flux Penetration, ffp) and upper critical field Hc2 was extracted. The thermodynamic critical field Hc, superheating field Hsh and superconducting parameters of samples with different treatments was calculated from the determined reversible magnetization curves. Hsh of doped samples is obviously smaller than that of un-doped samples, which may be a possible reason for the reduction of achievable accelerating gradient in SRF niobium cavities after nitrogen doping treatments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)