Nanosecond pulsed field emission from single-gate metallic field emitter arrays fabricated by molding

Abstract

Electrically gated pulsed field emission from molybdenum field emitter arrays was studied. Single-gate field emitter array devices supported by metallic substrates were fabricated by a combination of molding and a self-aligned gate process. Devices were tested in a low-inductance cathode holder compatible with the high-acceleration electric field of a pulsed diode gun. Pulsed field emission down to 1.1 ns was observed for single-gate devices with 1.2ϫ 10 3 -1.2ϫ 10 5 emitter tips with 5 m array pitches. Integrating the field emitter arrays in a high-voltage pulsed diode gun, the authors demonstrated nanosecond field emission at an acceleration field of 30 MV/m at the cathode surface and acceleration of the field emission electron beam up to 300 keV. In addition, transverse beam emittance of the single-gate devices was measured with two different array sizes.

Fabrication of metallic double-gate field emitter arrays and their electron beam collimation characteristics

“…In addition, a detailed comparison of the beam characteristics and the gate structures between FEA1 and FEA3 indicated that further improvement of the beam collimation can be achieved by optimizing the G ext aperture. The planar G col surface of our FEAs is likely to be advantageous for the operation in high acceleration electric fields of 10 MV/m and above 10,11 by reducing the probability of parasitic emission from the top surface and subsequent vacuum breakdown.…”

“…Research on field emitter arrays (FEAs) has been actively pursued [1][2][3][4][5][6][7][8][9][10][11][12][13] with the aim of realizing high current and high current density cathodes, e.g., for compact microwave vacuum electronic amplifiers, such as traveling wave tubes (TWTs) [14][15][16][17] and compact free electron lasers. 7,18 FEAs are expected to help simplify the gun design and extend the operation range of such TWTs.…”

Field emission beam characteristics of single metal nanotip cathodes with on-chip collimation gate electrode

“…This makes the nanofabricated metal nanotip emitters with on-chip gate electrodes attractive for many applications since the electron emission can be switched with the application of a low gate potential on the order of 100 V independently from the acceleration field. 9,10 In fact, integration of the single-gate field emission array (FEA) into a combined diode-RF cavity electron gun and stable subnanosecond pulsed field emission operation under the acceleration field up to 30 MV/m has been reported recently. 9 Further, highly collimated electron beams can be generated from double-gate FEAs by adding a collimation gate electrode on top of the electron extraction gate electrode and individually collimating the field emission beamlet.…”

“…9,10 In fact, integration of the single-gate field emission array (FEA) into a combined diode-RF cavity electron gun and stable subnanosecond pulsed field emission operation under the acceleration field up to 30 MV/m has been reported recently. 9 Further, highly collimated electron beams can be generated from double-gate FEAs by adding a collimation gate electrode on top of the electron extraction gate electrode and individually collimating the field emission beamlet. 11 We note that this is crucial to generate the high intrinsic brilliance FEA beam.…”

Picosecond electrical switching of single-gate metal nanotip arrays

“…1 Recently, a different approach was used to generate subnanosecond electrically gated electron pulses. 2,3 In these studies, FEAs with relatively high gate capacitance (200-400 pF) but with small substrate resistance below $10 À3 X ( Fig. 1) were used.…”