Field emitter arrays for plasma and microwave source applications

Abstract

Field emitter arrays (FEAs) stand to strongly impact device performance when physical size, weight, power consumption, beam current, and/or high pulse repetition frequencies are an issue. FEAs are capable of instant ON/OFF performance, high brightness, high current density, large transconductance to capacitance ratio, and low voltage operation characteristics. Advanced microwave power tubes, and in particular, inductive output amplifiers, are by far the most technically challenging use to date. Other important uses include, e.g., electron sources for micropropulsion systems–Hall thrusters–and tethers for satellites, and (the most widely pursued application) field emission displays. The characteristics of field emitters that make them attractive to such applications shall be surveyed. A thorough analytical model of a field emitter array, beginning with a review of the nature of field emission and continuing with an analytical model of a single emitter and the operation of an array of emitters, shall be presented. In particular, attention shall be directed towards those features of FEAs that render them attractive as cold cathode candidates for electron beam generation. Tip characteristics, such as emission distribution, and array operation, such as space charge effects, will be analyzed in the context of the model. Finally, restricting attention to microwave applications, the performance of a tapered-helix inductive output amplifier to highlight the advantages of high frequency emission gating of the electron beam in a power tube shall be investigated.

Analysis and simulation of anode heating due to electron field emission

“…The distribution of energy deposited into the anode through scattering can be seen in Fig. 4 for an applied field of 5 . In the distribution shown, 10 million electrons were used to achieve the smooth contours.…”

“…The product of the transmission coefficient of (3) and the differential supply function of (2) provides the number of electrons emitted per second per unit area per unit energy per unit solid angle (5) We note that is similar in form and function to intensity in radiation heat transfer. This function can be integrated over energy and solid angle to provide the emitted current density (6) where is the azimuthal angle of emission (see Fig.…”

“…Jensen [5] provided a recent review of applications in electronics. Due to the high electron mobility in vacuum, vacuum integrated circuits could provide significant increases in speed as compared to solid-state integrated circuits.…”

CMOL: Second life for silicon?

“…However, in order to overcome the CMOS/nanodevice interface problems pertinent to earlier proposals, in CMOL circuits the interface is provided by pins that are distributed all over the circuit area, on the top of the CMOS stack. (Silicon-based technology necessary for fabrication of pins with nanometer-scale tips has been already developed in the context of fieldemission arrays [19].) As Fig.…”

Large field emission current and density from robust carbon nanotube cathodes for continuous and pulsed electron sources

“…For X-ray generation, it requires a current density higher than 0.1-1 A cm −2 , and to get high-resolution X-ray image, the peak current should maintain tens of milliampere emission [16,17]. For applications in vacuum microwave devices, radar and communications, even higher emission current and density (in the order of 10 −1 A corresponding to density of 2-10 A cm −2 ) are required [3,18,19]. Table 1 summarizes the recent studies on field emission performance of CNT emitters.…”