Energetic Condensation Coating of NbTiN Thin Films for SRF Accelerator Applications

Statement of the Problem or Situation that is Being Addressed Describe the problem or situation being addressed. The DOEs and publics interest in the problem should be clearly stated (typically one to three sentences). High Energy Physics has a number of superconducting radiofrequency accelerator user facilities. The costs to build these facilities are large and materials costs can range upwards of 30-40%. Nb is the material of choice for the SRF cavities in these accelerators, however, Nb material costs are upwards of $300/lb for the bulk material. In order to reduce costs for new facilities a way must be found to reduce material costs. Statement of How this Problem or Situation is Being Addressed Describe how this problem or situation is being addressed. The overall objective or approach of the combined Phase I and Phase II projects should be clearly stated (typically one to two sentences). Alameda Applied Sciences Corporation proposes to deposit a superconducting layer of NbTiN on the inside surface of Cu cavities. Fabricating cavities out of bulk Cu would lead to a decrease in material costs while the NbTiN thin film would still maintain the low surface resistance of superconducting materials. Since NbTiN has a ~2x higher transition temperature compared with Nb further cost reductions could be realized by operating these cavities at higher temperatures. Statement of What is to be done in Phase I/II - In Phase I NbTiN will be deposited on small scale substrates and analyzed for stoichiometry as well as RRR and transition temperature. In Phase II, a Cu cavity will be coated with NbTiN and the SRF properties measured. Commercial Applications and Other Benefits Summarize the future applications and/or public benefits if the project is carried over into Phase II and beyond. Do not repeat information already provided above. The production of low cost SRF cavities has applications in all of todays SC particle accelerators, such as accelerator light sources and spallation neutron sources. As a secondary commercial benefit, TiN films have applications as hard and corrosion resistant coatings in the oil/gas and chemical industry as well as applications in RF couplers as a secondary electron emission inhibitor.