Optimization of Ar/CL2 plasma parameters used for SRF cavity etching
We are pursuing the development of environmentally friendly dry etching of superconducting radio frequency (SRF) cavities in Ar/CL2 discharges. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after plasma etchings are equal to or better than wet etching processes. The plasma properties inside the single cell SRF cavity depend significantly on frequency, pressure and power. To understand the plasma properties and chemical kinetics of plasma etching process inside a single cell cavity, we are using a specially-designed cavity with 20 sample holders symmetrically distributed over the cell. These holders are being used for niobium coupon etching as well as diagnostic ports for optical measurements. Multiple optical probes with optical fibers have been utilized for emission spectroscopy measurements. A power supply in the radio frequency regime (100 MHz) and another power supply in the microwave frequency regime (2.45 GHz) are used to produce plasma inside the cavity. The plasma parameters at different pressures and power levels in combination with the analysis of the niobium sample etched will be used to determine the adequate frequency regime for plasma etching of Nb cavities.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1994797
- Report Number(s):
- JLAB-ACC-11-1522; DOE/OR/23177-6942
- Resource Relation:
- Conference: SRF 2011, Chicago, IL USA, July 21, 2011
- Country of Publication:
- United States
- Language:
- English
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