Over the last decade much attention was given in increasing the quality factor of superconducting radio frequency cavities by impurity doping. Prior to the era of doping, the final cavity processing technique to achieve the high accelerating gradient includes the "in-situ" low temperature baking of SRF cavities at temperature ∼ 120 • C for several hours. Here, we present the results of a series of measurements on 1.3 GHz TESLA shape single-cell cavities with successive low temperature baking at 120 • C up to 96 hours. The experimental data were analyzed with available theory of superconductivity to elucidate the effect of the duration of low temperature baking on the superconducting properties of cavity materials as well as the rf performance. In addition, the rf loss related to the trapping of residual magnetic field refereed as flux trapping sensitivity was measured with respect to the duration of 120 • C bake.

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We present the cost-effective production of superconducting radio frequency (SRF) cavities made of medium grain (MG) niobium (Nb) discs directly sliced from forged and annealed billet. This production method provides clean surface conditions and reliable mechanical characteristics with sub-millimeter average grain size resulting in stable SRF cavity production. We propose to apply this material to particle accelerator in the science and industrial applications. The science applications require high field gradients(≥ 30 MV/m) particularly in pulsed mode. The industrial applications require high Q 0 values with moderate gradients (∼ 20 MV/m) in CW mode operation. This paper describes the MG Nb disc production recently demonstrated and discusses future prospects for application in advanced particle accelerators in the science and industrial applications.

We have successfully fabricated two 1.5 GHz single cell from forged ingot of residual resistivity ratio ~100.• Both cavities are processed with bulk EP, followed by 650 C/10 hrs annealing. • The rf performance of one of the cavity tested to this date is limited ~14 MV/m. Multipacting barrier was predicted at this gradient and it may be the likely the cause of quench.Oscillating superleak transducer (OST) sensors were used during rf measurements to detect the quench location and data are under review.

We would like to acknowledge to all the technical staffs helped processing and handling of the cavity during the pandemic.