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MLF Experimental Report
17&Project No.

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 Date of Report
April 23, 2013.)3+ Name of responsible person

2012B0245
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Stefanus HARJO
Title of experiment.)

Name of Instrument/TBL No.U

Study of strain behavior in Rutherford-type A15 superconducting

TAKUMI/BL-19

cables for future particle accelerators Date of Experiment83+Name of principal investigatorJan. 14-15, 2013

Tatsushi NAKAMOTO

Feb. 9-11, 2013

 Affiliation
High Energy Accelerator Research Organization (KEK)098!9$J(MNDIQSP9*9(2'O9/4BGA;:T59-"J@HU
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 0 Name of sample(s) and chemical formula, or compositions including physical form.
A RHQ-Nb3Al superconducting wire: φ1 mm, 50 mm long, heat-r eacted at 800 °C for 10 hours in advance.
Composite of Nb3Al, Cu, Ta, Nb. 3 wires.

SUS 304 cylindrical rod: 30 mm in a diameter, 39 mm long.

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Experimental method and results. If you failed to conduct experiment as planned, please describe reasons.
Two different experim ents were carried out
in 2013B: axial tensile strain behavior ofNb3Al
superconducting wire at 6 K was measured in the fi rst beam time (Jan. 14-15, 2013) while the systemcommissioning of the compression jig at low temperature was made in the second beam time (Feb. 9-11, 2013).
Figure 1 shows sample setup in the cryogenic
load frame for the first experiment . Three Nb 3Al
superconducting wires were connected to chucks by soldering. Besides, the stack of Nb 3Al superconducting
wires was directly attached to the cold stage for the residual strain measurement with better statistics. T he wire
samples were inclined at 45 degree w ith respect to the in cident neutron beam so that both axial and transversal
strains of N b3Al can be determ ined at sam e time. Axial tensile loading and unloading were applied to the 3
Nb3Al wires up to 200 MPa in several steps for the ne utron diffraction m easurement at 6 K to observe theinternal strain behavior. Due to the trouble of the M LF target, the beam tim e was reduced to be 1 day. For thisreason, the samples were cooled down to the lowest temperature prior to the beam time to allocate the sufficientmeasurement time at each loading step within a limited beam time. The measurement was successful and clear
shift of the diffraction peaks were observed as a function of applied axial tensile stress.

12.  Experimental method and results (continued)

The second experiment was dedicated for the system commissioning of the compression jig, which was newly
developed for simulating the internal stress in the supe rconducting coil, at low temperature using neutron beam.
Figure 2 shows the sam ple setup of the com pression jig. For this system commissioni ng, a well-known stainlesssteel rod (SU S304) was utilized to confirm the valid ity of the neutron diffraction m easurement at lowtemperature. The compressive loading up to 50 kN, which was the maximum limit of the load frame, was applied
to the sample. The stress-strain behavior was successfully obtained by the neutron diffraction measurement.
However, the sample temperature was only cooled down to 30 K because the conduction cooling paths fromthe cold stage w ere insufficient in com parison with the substantial volume of the com pression jig (~20 kg).
Besides, the unwanted background neutr on from the crosshead was observed. For the next experim ent, someimprovement for the jig will be necessary.

Figure 1. Photograph of sample se tup for the first experim ent: 3 Nb 3Al wires inparallel attached to the chucks.

Figure 2. Photograph of sample setup for the sec ond experiment: a cylindrical rod of SUS304 (39mm long, 30 m m in a diam eter) is sandwiched by the crossheads of the com pression jig, where
the tensile loading of the load frame is converted to the compressive loading on the sample.

2