arXiv subjects

J. Ozelis

Publications and source records attributed to J. Ozelis.

9 recordsLinked to original sources

arXiv2026

Heat load measurements for the PIP-II pHB650 cryomodule

Phase-3 testing of the pHB650 cryomodule at the PIP-II Injector Test Facility was conducted to evaluate the effectiveness of heat load mitigations performed after earlier phases of testing and to continue pinpointing any sources of unexpectedly high heat loads.. The programme measured HTTS, LTTS, and 2 K isothermal/non-isothermal loads under "standard", "linac", and "simulated dynamic" operating modes, recording data both inside the cryomodule and across the bayonet can circuits. Thermal-acoustic oscillations were eliminated by replacing the original G10 cooldown-valve stem with a stainless-steel stem fitted with wipers. A newly developed Python script automated acquisition of ACNET data, performed real-time heat-load calculations, and generated plots and tables that were posted to the electronic logbook within minutes, vastly reducing manual effort and accelerating feedback between SRF and cryogenics teams. Analysis showed that JT heat-exchanger effectiveness and temperature stratification in the two-phase and relief piping strongly influence the observed loads and helped isolate sources of excess heat. The campaign demonstrates that rigorous pre-test planning, real-time diagnostics, and automated reporting can improve both accuracy and efficiency, providing a template for future PIP-II cryomodule tests and for implementing targeted heat-load mitigations.

physics.acc-ph↗

arXiv2024

Performance of PIP-II High-beta 650 Cryomodule After Transatlantic Shipping

After shipment to the Daresbury Lab and return to Fermilab, the prototype HB650 cryomodule underwent another phase of 2K RF testing to ascertain any performance issues that may have arisen from the transport of the cryomodule. While measurements taken at room temperature after the conclusion of shipment indicated that there were no negative impacts on cavity alignment, beamline vacuum, or cavity frequency, testing at 2K was required to validate other aspects such as tuner operation, cavity coupling, cryogenic system integrity, and cavity performance. Results of this latest round of limited 2K testing will be presented.

physics.acc-ph↗

arXiv2024

Impact of Solenoid Induced Residual Magnetic Fields on The Prototype SSR1 CM Performance

A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses was successfully assembled, cold tested, and accelerated beam in the framework of the PIP-II project at Fermilab. The impact of induced residual magnetic fields from the solenoids on performance of cavities is presented in this contribution. In addition, design optimizations for the production cryomodules as a result of this impact are highlighted.

physics.acc-ph↗

arXiv2024

Latest Development of Electropolishing Optimization for 650 MHz Niobium Cavity

Electropolishing (EP) of 1.3 GHz niobium superconducting RF cavities is conducted to achieve a desired smooth and contaminant-free surface that yields good RF performance. Achieving a smooth surface of a large-sized elliptical cavity with the standard EP conditions was found to be challenging. This work aimed to conduct a systematic parametric EP study to understand the effects of various EP parameters on the surface of 650 MHz niobium cavities used in the Proton Improvement Plan-II (PIP-II) linear accelerator. Parameters optimized in this study provided a smooth surface of the cavities. The electropolished cavity showed significantly a higher accelerating gradient meeting baseline requirement and qualified for further surface treatment to improve the cavity quality factor.

physics.acc-ph↗

arXiv2023

The Evaluation of Mechanical Properties of LB650 Cavities

The PIP-II project's LB650 cavities could potentially be vulnerable to mechanical deformation because of the geometric shape of the cavity due to reduced beta. The mechanical property of the niobium half-cell was measured following various heat treatments. The 5-cell cavities were tested in a controlled drop test fashion and the real-world road test. The result showed that the 900 $°$C heat treatment was compatible with cavity handling and transportation during production. The test provides the bases of the transportation specification and shipping container design guidelines.

physics.acc-ph↗

arXiv2022

Design, Manufacturing, Assembly, Testing, And Lessons Learned Of The Prototype 650 Mhz Couplers

Six 650 MHz high-power couplers will be integrated into the prototype High Beta 650 MHz (HB650) cryomodule for the PIP-II project at Fermilab. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life-cycle, including manufacturing, assembly, testing, conditioning, and the lessons learned at each stage.

physics.acc-ph↗

arXiv2018

Commissioning And First Results From The Fermilab Cryomodule Test Stand

A new test stand dedicated to Superconducting Radiofrequency (SRF) cryomodule testing, CMTS1, has been commissioned and is now in operation at Fermilab. The first device to be cooled down and powered in this facility is the prototype 1.3 GHz cryomodule assembled at Fermilab for LCLS-II. We describe the demonstrated capabilities of CMTS1, report on steps taken during commissioning, provide an overview of first test results, and survey future plans.

physics.acc-ph↗

arXiv2013

High Gradient Tests of the Fermilab SSR1 Cavity

In Fermilab we are build and tested several superconducting Single Spoke Resonators (SSR1, β=0.22) which can be used for acceleration of low beta ions. Fist two cavities performed very well during cold test in Vertical Test Station at FNAL. One dressed cavity was also tested successfully in Horizontal Test Station. Currently we are building 8 cavity cryomodule for PIXIE project. Additional 10 cavities were manufactured in the industry and on-going cold test results will be presented in this poster.

physics.acc-ph↗

arXiv2012

Investigations of surface quality and SRF cavity performance

Magnetic field enhancement has been studied in the past through replica and cavity cutting. Considerable progress of niobium cavity manufacturing and processing has been made since then. Wide variety of single cell cavities has been analyzed through replica technique. Their RF performances were compared in corresponding to geometric RF surface quality. It is concluded that the surface roughness affects cavity performance mostly in secondary role. The other factors must have played primary role in cavity performance limitations.

physics.acc-ph↗