Author: Andrews, H.L.
Paper Title Page
TUP073
Photoemission from Diamond Field-Emitter Arrays  
 
  • V.N. Pavlenko, H.L. Andrews, R.L. Fleming, A. Piryatinski, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program for this work.
We present experimental data on photoemission from diamond films, outlining future studies of diamond field emitter arrays (DFEAs) operation in photoemission mode. Nano-tipped field emitters are attractive types of electron sources for dielectric laser accelerators (DLAs),* whose ability to generate coherent electron bunches in laser-triggered mode has been successfully demonstrated.** To explore applicability of diamond field emitters to DLAs, we will measure spectral response (quantum efficiency vs photon energy) of DFEAs in the limit of low electric fields. We will compare the measurements on DFEAs with different densities and tip radii against bulk flat diamond photoemission. The results will be used to validate the a photoemission model that takes into account quantum confinement effects at the nano-tips of the pyramids.
* E. A. Peralta et al., Nature 503, 91 (2013)
** R. Ganter et al., Phys. Rev. Lett. 100, 064801 (2008); D. Ehberger et al., Phys. Rev. Lett. 114, 227601 (2015)
 
 
WEP015 Current Experimental Work with Diamond Field-Emitter Array Cathodes 1
 
  • H.L. Andrews, R.L. Fleming, J.W. Lewellen, K.E. Nichols, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • B.K. Choi
    Vanderbilt University, Nashville, USA
 
  Funding: We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program for this work.
Diamond Field-Emitter Array (DFEA) cathodes are arrays of micron-scale diamond pyramids with nanometer-scale tips, thereby providing high emission currents with small emittance and energy spread. To date they have been demonstrated in a close-diode configuration, spaced only a few hundred microns from a solid anode, and have shown very promising results in terms of emittance, energy spread, and per-tip emission currents. We present recent results investigating DFEA performance in a large-gap configuration, such that the cathodes are a few millimeters from a solid anode, and show that performance is the same or better as the close-diode geometry previously studied. However, array performance is still limited by anode damage. We are redesigning our cathode test stand to overcome the inherent limitations of a solid anode, allow for transport of the emitted beam, and further explore real-world DFEA performance.
 
 
WEP016 Modeling of Diamond Field-Emitter Arrays for High-Brightness Photocathode Applications 1
 
  • C. Huang, H.L. Andrews, B.K. Choi, R.L. Fleming, T.J. Kwan, J.W. Lewellen, D.C. Nguyen, K.E. Nichols, V.N. Pavlenko, A. Piryatinski, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work performed under the auspices of the U.S. DOE by the LANS, LLC, Los Alamos National Laboratory (LANL) under Contract No. DE-AC52-06NA25396. Work supported by the LDRD program at LANL.
Dielectric Laser Accelerator (DLA) is capable of generating high output power for an X-ray free-electron laser (FEL), while having a size 1-2 orders of magnitude smaller than existing Radio-Frequency (RF) accelerators. Single Diamond Field-Emitter (DFE) or array of such emitters (DFEA) can be employed as high-current ultra-low-emittance photocathodes for compact DLAs. We are developing a first principle semi-classical Monte-Carlo (MC) emission model for DFEAs that includes the effects of carriers' photoexcitation, their transport to the emitter surface, and the tunnelling through the surface. The electronic structure size quantization affecting the transport and tunnelling processes within the sharp diamond tips is also accounted for. These aspects of our model and their implementation and validation, as well as macroscopic electromagnetic beam simulation of DFE are discussed.