| DATE: |
2014-06-16 10:00 - 11:00 |
| PLACE: |
Large Meeting Room, 1st floor, Building-2 |
| TITLE: |
SRF Technology Comes Full Circle |
| CONTACT: |
LC Project Office (A. Yamamoto, PHS: 4063) |
| SPEAKER: |
Dr. Ganapati Myneni (JLab) |
| LANGUAGE: |
English |
| ABSTRACT: |
The Superconducting Radio Frequency (SRF) Technology during its formative years, at the High energy Physics Laboratory in Stanford University, was based on low purity electron beam melted niobium ingots. Though the SRF cavities machined from such low impurity ingot niobium performed well with impressive quality factors with buffered chemical
polishing (~101l @ 1.2 K) and peak magnetic fields (Hpk~108 mT), cavities with reproducible performance could not be produced reliably. The main reason for the failure in the advancement of the SRF technology
at that time appears to be recontamination of the cavity surfaces with particulates and or hydrocarbons. During the same period (early 1970”Ēs) electro polished reactor grade polycrystalline niobium cavities reached
record peak fields of 159 mT.
SRF cavities for several completed projects (CEBAF upgrade, SNS and KEKB) have been built with high purity polycrystalline niobium with residual resistance ratio (RRR) greater than 250. Recently, XFEL at DESY
is again based on high RRR polycrystalline niobium with RRR greater than 300. The procedures and processes used from the initial production of the high RRR polycrystalline niobium sheets to the finished cavities are complex, numerous and very expensive thereby making this technology unfriendly for the vast majority of possible technology spin-offs.
CBMM - Jefferson Lab invented ingot niobium technology - the use of niobium sheets sliced directly from the ingots can be expected to change
the SRF Technology outlook with fewer, and more stream lined, production processes that will not only be cost effective but also generate high yield.
In this talk I will show that less stringent commercial niobium specifications are acceptable and explore the processes and procedures that will lay the
foundation for producing SRF cavities with good quality factors at high peak magnetic fields in order to make this technology friendlier for future scientific
and technological applications. |
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