GIGA-ELECTRON VOLT FIELD, RF WINDOWS AND CARBON NANOTUBE (CNT) CATHODE DEVELOPMENT FOR CRYOGENIC LINEAR ACCELERATORS AND HIGH POWERED RADIO FEQUENCY
Abstract
The goals of this research will be to achieve extreme high electric field performance of near to giga-electron volts (GeV)/meter for high-powered radio frequency (RF) devices and cryogenic RF linear accelerator cavities. Additional goals of the research are to develop cathodes for electron beams from LINACs and high-powered RF devices that achieve beyond state-of-the-art current, perveance and low emittance without vacuum breakdown or outgassing. These cathode technologies include voltage pulsed, combined field-emission/secondary electron emission and mid-wave infrared laser ultra-short pulsed tunneling ionization based carbon nano-tube (CNT) and/or Boron Nitride Nano-tube (BNNT) fiber and film cathodes. Cryogenic copper (Cu) RF cavities (operated below 40 K) have been shown by UCLA and SLAC to permit much higher RF fields, extending the peak surface fields supported in a cavity to 500 MV/m . With these field levels, dark current produced via field emission presents challenges in the use of such frontier accelerators. As such, one of the most important goals of the proposed research is reduction of field emitted dark current. The INFN-LNF (Frascati) is developing robust surface coatings such as molybdenum trioxide (MoO3) and silicon oxynitride (SiON) to accomplish this. This effort will be greatly enhanced by collaboration with Cambridge’s/AFRL, in that laser surface melting (LSM) may provide a key basis for yielding a substrate with an improved underlying grain structure, is crystalline in nature and is depleted of H2 and other contaminate gases. The diagnostic and test capabilities of DAF are also highly advantageous in characterizing the developed materials attributes and helping give a physics understanding of the process of LSM and surface coating deposition. The intent is to investigate the impact of LSM on improving the surface conductivity in the cryogenic case, thus extending the advantages of cryogenic Cu high field RF cavities further.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2021
- Source ID
- FA86552017049
Entities
People
- William O Neill
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Cambridge