Student:	Şeyda DUMAN
Supervisor:	Prof. Alev AYDINER
Department:	Fizik
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University Turkey

Title of the Thesis:	THE EFFECT OF WATER JET METHOD ON THE STRUCTURAL AND PHYSICAL PROPERTIES OF THE Y123 + MOLAR % X Y211 (X = 20, 25, 30) SUPERCONDUCTING SAMPLES WELDED WITH SOLDER MATERIAL FABRICATED BY MELTING METHODS
Level:	Ph.D.
Acceptance Date:	29/4/2022
Number of Pages:	137
Registration Number:	Di1492

Summary:

In this study, it is aimed to convert welded TSMG YBCO single crystals using different

Y211 and molar 20% Ag2O doped YBCO samples produced using melting methods into coil using

water jet and to examine the effects of water jet on the welding region in order to increase their use

in technological applications.

In this context, single crystal samples with Y123 + x% (x=20, 25, 30) Y211 compositions

were fabricated in two groups using Nd123 seed crystal with TSMG method. MPMG and TSMG

processed solder samples with x% (x=20, 25, 30) Y211 and 20% Ag2O additions were fabricated in

two groups for welding of TSMG YBCO samples. Using the results of the trapped magnetic field

measurements, the samples with the same compositions and with close trapped field values were

chosen and the samples were welded by appropriate thermal process after placing a mass of 1.5 kg

on the top surface of the stacked samples. A group of welded samples were turned into the coils by

drilling from their center axes using the water jet method. In order to examine the effects of the

water jet on the welding region, resistivity and magnetization measurements, activation energy

calculation and fluctuation induced conductivity analysis of the small pieces cut from the welded

samples were done.

Trapped field values of Y123 + 25%Y211 samples were found to be relatively higher than

other Y123 + x% (x=20, 30) samples. It was observed from the magnetization measurements that

the water jet drilling method adversely affected the current carrying capacity of the samples,

welded by a solder material produced with MPMG method. It was found that the activation energy

values calculated from the resistivity measurements of the samples with 25% Y211 addition were

higher.

Key Words: TSMG YBCO, Welding method with solder material, Water jet method, Critical

current density, Activation energy, Fluctuation induced conductivity