Design Study of a Test Cavity for Evaluating RF Critical Magnetic Field of Thin-Film Superconductor
Superconducting cavities of higher gradient has been demanded in various fields of the accelerator science. Also, according to the Technical Design Report (TDR) of International Linear Collider (ILC), the higher gradient of 45 MV/m is required in the second stage of ILC. To realize such higher gradient, several methods are proposed. One of such methods is to coat multi-layer thin-film superconductor on the inner surface of RF cavity where the thin film increases the RF critical field on the
... al field on the inner surface of the cavity. To demonstrate the RF performance of thin-film structure on a small coupon sample, we designed the RF mushroom-shaped cavity with which the RF critical magnetic field is measured on a thin-film coupon sample set on the inner surface of the cavity. If the RF cavity is cooled down below the critical temperature of thin-film superconductor with supplying RF power, the heat dissipation might be measured on the coupon sample in the cavity. We designed the shape of the cavity so as to produce a strong RF magnetic field parallel to the sample surface efficiently. We report the design, manufacturing and RF property measurements of the cavity in this presentation.