Ultrafast High-Brightness Electron Source

Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R & amp;D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultrashort bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact and inexpensive ultrafast high-brightness source. AES proposes an alternative scheme to achieve an ultrafast high-brightness electron beam through the radial bunch compression technique in an x-band photocathode radio frequency electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we will seek to approach 100 fs bunch length with 100 pC bunch charge. AES will demonstrate that the curved cathode compensation technique for achieving short electron bunches can be successfully utilized in an x-band rf photocathode gun to generate an ultrafast high-brightness electron beam with better beam parameters compared to the present state-of-the-art. A thorough beam dynamics study, along with a conceptual rf design and a basic thermal analysis will be performed. Commercial Applications and Other Benefits: Ultrafast high-brightness electron beams would be beneficial for advances in accelerator technology such as the laser wakefield acceleration sources, non-recirculating coherent synchrotron radiation sources and free electron lasers. This will have benefits both in bunch length and brightness of the beam as well as in reducing the capital cost of the system. It should also open up expanded areas of study using ultrafast electron diffraction. Thus, this proposed source could provide a promising potential to significantly extend the availability of such electron sources to a wider user community.