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Title: Current Experimental Work with Diamond Field-Emitter Array Cathodes

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  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
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DOE Contract Number:
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Resource Relation:
Conference: 38th International Free Electron Laser Conference ; 2017-08-20 - 2017-08-25 ; Santa Fe, New Mexico, United States
Country of Publication:
United States
Accelerator Design, Technology, and Operations; high-brightness cathodes

Citation Formats

Andrews, Heather Lynn. Current Experimental Work with Diamond Field-Emitter Array Cathodes. United States: N. p., 2017. Web.
Andrews, Heather Lynn. Current Experimental Work with Diamond Field-Emitter Array Cathodes. United States.
Andrews, Heather Lynn. 2017. "Current Experimental Work with Diamond Field-Emitter Array Cathodes". United States. doi:.
title = {Current Experimental Work with Diamond Field-Emitter Array Cathodes},
author = {Andrews, Heather Lynn},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =

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  • These are slides for a presentation at Stanford University. The outline is as follows: Motivation: customers for compact accelerators, LANL's technologies for laser acceleration, DFEA cathodes, and additive manufacturing of micron-size structures. Among the stated conclusions are the following: preliminary study identified DFEA cathodes as promising sources for DLAs--high beam current and small emittance; additive manufacturing with Nanoscribe Professional GT can produce structures with the right scale features for a DLA operating at micron wavelengths (fabrication tolerances need to be studied, DLAs require new materials). Future plans include DLA experiment with a beam produced by the DFEA cathode with fieldmore » emission, demonstration of photoemission from DFEAs, and new structures to print and test.« less
  • The Field Emitter Array (FEA) cathode possesses high emission potential (approx.30A/cm/sup 2/) at low applied voltages (100-200 volts) but performance has been hampered by non-uniform emission across the array. Poor emission uniformity is mainly related to small variations in emitter tip geometry (of the order of 10-100A), which cannot be rectified by present fabrication techniques. To improve emission uniformity from the arrays, this dissertation investigated the use of current-limiting resistors, individually dedicated to and in series with each emitter, to compensate for the differences in emission. A thin film of silicon was deposited on the backside of a ZrO/sub 2/-Wmore » composite chip (the substrate on which emitter structure was based) to form series resistors. Characterization of the silicon film was carried out in a SEM with a micromanipulator capable of making contact with a single tungsten pin so that direct I-V measurement of individual series resistors was possible. To supplement the experimental effort, a mathematical mode of the Current-Limited Field Emitter Array (CLFEA) cathode was devised. A study of the model indicated the Fowler-Nordheim (F-N) plot of resistor current-limited emission from an array would have an upturning curvature.« less
  • Successful application of field emitter array cathodes at microwave frequencies is dependent upon significant progress in emitter development. Two factors are of primary concern, namely, the transconductance and the array capacitance. To provide guidance in development of structures with minimum capacitance, a scaled, physical model of an emitter array has been developed and used to study qualitatively the effect of several geometrical and materials parameters on device capacitance. In this article the effects of an insulating versus a conducting substrate, and variation of the insulator film thickness, extractor aperture diameter, and extractor film thickness are reported. It is shown thatmore » the array capacitance is primarily determined by the details of the extractor aperture-emitter tip geometry, and is not influenced by the extractor to substrate spacing unless the insulator film thickness is substantially less than one-half the pin-to-pin spacing in the array. Although the results are not intended to be quantitative, it is estimated that the Georgia Tech field emitter array cathodes, based on oxide-metal composite materials composed of single-crystal tungsten emitter tips in an insulating zirconium dioxide matrix (substrate), display capacitances of the order of 1X10{sup -16} Farads/pin. 5 refs., 9 figs., 1 tab.« less
  • Microwave power tube cathodes set the most demanding performance standards for any application of field emitter arrays. The devices described in this work are fabricated at MCNC using a new process. The resulting devices have tips on 2 {micro}m columns and gate aperture diameters of less than 2 {micro}. The tips are formed by either anisotropic or isotropic etch techniques, and are oxidation sharpened to produce uniform emitters with tip radii less than 100 angstroms. Measurement of the electrical characteristics is performed by an automated data acquisition system. The current-voltage characteristics are then plotted in Fowler-Nordheim format. From this plotmore » and the RF impedance of the device, the parameters that determine the ultimate performance in a microwave tube can be extracted. Based on measurements of these high-performance arrays, a power gain of approximately 10 dB can be expected when these arrays are used as cathodes in an inductive output amplifier tube.« less