arXiv subjects

Sung Woo Youn

Publications and source records attributed to Sung Woo Youn.

5 recordsLinked to original sources

arXiv2021

First prototype of a biaxially textured YBa$_{2}$Cu$_{3}$O$_{7-x}$ microwave cavity in a high magnetic field for dark matter axion search

A high-quality factor microwave resonator in the presence of a strong magnetic field could have a wide range of applications, such as axion dark matter searches where the two aspects must coexist to enhance the experimental sensitivity. We introduce a polygon-shaped cavity design with bi-axially textured YBa$_{2}$Cu$_{3}$O$_{7-x}$ superconducting tapes covering the entire inner wall. Using a 12-sided polygon cavity, we obtain substantially improved quality factors of the TM$_{010}$ mode at 6.9 GHz at 4 K with respect to a copper cavity and observe no considerable degradation in the presence of magnetic fields up to 8 T. This corresponds to the first demonstration of practical applications of superconducting radio frequency technology for axion and other research areas requiring low loss in a strong magnetic field. We address the importance of the successful demonstration and discuss further improvements.

physics.ins-det↗

arXiv2020

Superconducting cavity in a high magnetic field

A high Q-factor microwave resonator in a high magnetic field could be used in a wide range of applications, especially for enhancing the scanning speed in axion dark matter research. In this letter, we introduce a polygon-shaped resonant cavity with commercial YBCO tapes covering the entire inner wall. We demonstrated that the maximum Q-factor (TM$_{010}$, 6.93 GHz) of the superconducting YBCO cavity was about 6 times higher than that of a copper cavity and showed no significant degradation up to 8 T at 4 K. This is the first indication of the possible applications of HTS technology to the research areas requiring low loss in a strong magnetic field at high radio frequencies.

physics.app-ph↗

arXiv2019

Maintaining high Q-factor of superconducting YBa$_2$Cu$_3$O$_{7-x}$ microwave cavity in a high magnetic field

A high Q-factor microwave resonator in a high magnetic field could be of great use in a wide range of fields, from accelerator design to axion dark matter search. The natural choice of material for the superconducting cavity to be placed in a high field is a high temperature superconductor (HTS) with a high critical field. The deposition, however, of a high-quality, grain-aligned HTS film on a three-dimensional surface is technically challenging. We have fabricated a polygon-shaped resonant cavity with commercial YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) tapes covering the entire inner wall and measured the Q-factor at 4 K at 6.93 GHz as a function of an external DC magnetic field. We demonstrated that the high Q-factor of the superconducting YBCO cavity showed no significant degradation from 1 T up to 8 T. This is the first indication of the possible applications of HTS technology to the research areas requiring a strong magnetic field at high radio frequencies.

physics.ins-det↗

arXiv2017

Magnetoresistance in copper at high frequency and high magnetic fields

In halo dark matter axion search experiments, cylindrical microwave cavities are typically employed to detect signals from the axion-photon conversion. To enhance the conversion power and reduce the noise level, cavities are placed in strong solenoid magnetic fields at sufficiently low temperatures. Exploring high mass regions in cavity-based axion search experiments requires high frequency microwave cavities and thus understanding cavity properties at high frequencies in extreme conditions is deemed necessary. We present a study of the magnetoresistance of copper using a cavity with a resonant frequency of 12.9 GHz at the liquid helium temperature in magnetic fields up to 15 T utilizing a second generation high temperature superconducting magnet. The observations are interpreted to be consistent with the anomalous skin effect and size effect. This is the first measurement of magnetoresistance at a high frequency (> 10 GHz) in high magnetic fields (> 10 T).

physics.ins-det↗

arXiv2016

Comment on "Axion Dark Matter Coupling to Resonant Photons via Magnetic Field"

A recent Letter, Phys. Rev. Lett. 116, 161804 (2016), claims that for typical dark matter axion search experiments using cylindrical haloscopes, the power gain depends on the relative position of a cavity with respect to the center of a solenoidal magnetic field due to different electric and magnetic couplings. We review this Letter and find a misinterpretation of the coordinate system. We correct this and see no dependence of the coupling strength on the cavity location and the electric and magnetic energies stored in a cavity mode are equal.

hep-ex↗