実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
9 May 2013

課題番号 Project No.

装置責任者 Name of responsible person

2012B0017

Aizawa Kazuya

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Investigation

ofdegradation

mechanism

inlarge-scale

BL No. 19

superconductor for fusion reactors

実施日 Date of Experiment

実験責任者名 Name of principal investigator

24 Nov. 2013 – 28 Nov. 2013

Tsutomu Hemmi

4 Dec. 2013 – 8 Dec. 2013

所属 Affiliation
JAEA
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
1) ITER CS conductor sample (solid): Nb3Sn, Nb, Cu, CuSn, Stainless steel (JK2LB), Cr
2) Nb3Sn Filaments (solid): Nb3Sn3) Nb3Sn Strand (solid): Nb3Sn, Nb, Cu, CuSn, Cr
4) Bent Nb3Sn Strand (solid): Nb3Sn, Nb, Cu, CuSn, Ti6Al4V
2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

As shown in Figure 1, an incident beam is diffracted at a selected position of the conductor sample. The
TOF diffracted beam is collected by a pair of detector, which is located at 90 degree angles from theincident beam, in order to determine internal strains for axial and lateral directions simultaneously. The
measured gauge volume of 7 x 2 x 16 mm3 in the conductor sample was determined by the incident slit tospecify the measured position of 7 mm in height and 16 mm in width, and a pair of radial collimator to
specify the measured position of 2 mm in thickness. The sample conductor was turned over to measure forthe lower loading side (LLS) and the higher loading side (HLS) to have same path of the neutron beam.
To evaluate internal strains in conductor sample, neutron diffraction measurements were performed atroom temperature after the SULTAN testing. Figure 2 shows the neutron diffraction profiles for Nb3Sn(211) at the LLS and the HLS of the field center and 1150 mm from the field center of the CSJA01 L beforecutting. There is difference in neutron diffraction peak profile of Nb3Sn (211) between the LLS and theHLS of the field center. HWHM is the difference between the HWHMs of the sample and the Nb3Sn
strands to show the broadening of the neutron diffraction profile. The bending of the Nb3Sn was found atthe LLS of the field center since the broadening of the neutron diffraction peak profile of the LLS of thefield center was observed.
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2. 実験方法及び結果（つづき） Experimental method and results (continued)

1.2

16

32.6

Intensity (a.u.)

2

1.0
0.8
0.6
0.4
0.2
0.0
-0.2

0.212

0.214

0.216

0.218

0.220

Lattice spacing (nm)Figure 1 Schematic diagrams of measurement

Figure 2

Differences in neutron diffraction profile.

Figure 3 shows the internal strain evaluated from the diffraction planes of Nb3Sn (210), (211), (320) and(321) as averages weighted by the integral intensities of each diffraction peak profile before/after cutting of
the conductor sample. The internal strain of Nb3Sn was changed to the tensile side and broadened by thecyclic testing at the LLS of the HFZ. The internal strain was released by cutting since the thermally induced
residual strain generated by the difference in thermal contraction between the cable and the jacket waschanged.

10-0.1
5-0.2-0.3

Ave. strain (%)

0.00.1150.0
10-0.1
5-0.2
-0.3

0-0.4

0-0.4

0500
1000
1500
Position from field center (mm)(a) before cutting
Figure 3External field (T)15External field (T)Ave. strain (%)

0.10500
1000
1500
Position from field center (mm)(b) after cutting

Results of internal strain for Nb3Sn before/after cutting.

The neutron diffraction measurements of the conductor sample before/after cutting were performed toinvestigate the Tcs degradation of the conductor sample. As a result of the neutron diffraction measurement,
the large bending at the LLS of the HFZ was observed. Therefore, it is concluded that the Tcs degraded
position of the conductor sample due to the cyclic loading was the LLS of the HFZ in the conductor sample.
The large bending was considered as an origin of the strand buckling due to the large void generated by thetransverse electromagnetic loading and the thermally induced residual strain generated by the difference inthe thermal contraction between the cable and the jacket.
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