IPAC2021 - List of Authors (Umemori, K.)

Paper	Title	Page
MOPAB383	Pressure Test for Large Grain and Fine Grain Niobium Cavities	1173
	M. Yamanaka, T. Dohmae, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, K. Yoshida KEK, Ibaraki, Japan K. Enami Tsukuba University, Ibaraki, Japan
	The pressure test was performed using a fine grain (FG) and a large grain (LG) niobium cavities. The cavity is 1.3 GHz 3-cell TESLA-like shape. The cavity was housed in a steel vessel. Water is supplied into the vessel and the cavity outside is pressurized. The applying pressure and the natural frequency of cavity were measured during the pressure test. The FG and LG cavities were deformed greatly and the pressure dropped suddenly at 3.4 MPa and 1.6 MPa, respectively. The frequency shifted up to 3.4 MHz and 1.3 MHz, respectively. There was no leak after the pressure test, so the cavity did not rupture under above pressure. The result of the pressure at LG cavity is less half than that of the FG cavity. We calculated the stress distribution in the structure by applying outer water pressure using a FEM. The maximum stress at cell when above test pressure is applied, are 146 MPa in FG and 73 MPa in LG, respectively. These stresses are similar to tensile strength of niobium specimen measure by ourselves. The result of pressure tests agrees well with the calculation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB383
About •	paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 28 August 2021
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TUPAB017	Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac	1375
	Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong KEK, Ibaraki, Japan V.S. Kashikhin Fermilab, Batavia, Illinois, USA
	A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Pressure Test for Large Grain and Fine Grain Niobium Cavities

1173

M. Yamanaka, T. Dohmae, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, K. Yoshida
KEK, Ibaraki, Japan
K. Enami
Tsukuba University, Ibaraki, Japan

The pressure test was performed using a fine grain (FG) and a large grain (LG) niobium cavities. The cavity is 1.3 GHz 3-cell TESLA-like shape. The cavity was housed in a steel vessel. Water is supplied into the vessel and the cavity outside is pressurized. The applying pressure and the natural frequency of cavity were measured during the pressure test. The FG and LG cavities were deformed greatly and the pressure dropped suddenly at 3.4 MPa and 1.6 MPa, respectively. The frequency shifted up to 3.4 MHz and 1.3 MHz, respectively. There was no leak after the pressure test, so the cavity did not rupture under above pressure. The result of the pressure at LG cavity is less half than that of the FG cavity. We calculated the stress distribution in the structure by applying outer water pressure using a FEM. The maximum stress at cell when above test pressure is applied, are 146 MPa in FG and 73 MPa in LG, respectively. These stresses are similar to tensile strength of niobium specimen measure by ourselves. The result of pressure tests agrees well with the calculation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB383

About •

paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 28 August 2021

Export •

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

TUPAB017

Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac

1375

Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong
KEK, Ibaraki, Japan
V.S. Kashikhin
Fermilab, Batavia, Illinois, USA

A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017

About •

paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021

Export •

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