An improved gridded microwave tube is provided, the tube containing a cold cathode, an anode, and a grid located between the anode and cathode. In one embodiment, the cold cathode has a refractory metal substrate and carbon nanotube emitters, the emitters having a diameter of 1 to 300 nm and a length of 0.05 to 100 µm. The grid-cathode spacing is 1 to 100 µm, the grid contains apertures having a maximum dimension of 0.5 to 100 µm, and the grid thickness is 0.5 to 100 µm. Emission from the cathode directly onto the grid material itself, which undesirably heats the grid, is reduced by either (a) the presence of a shadow mask between the grid and the emitters or (b) selective formation of the emitters in locations that correspond to the grid apertures. The microwave tube operates at a frequency of greater than 0.5 GHz, advantageously greater than 2 GHz.

Microwave vacuum tube device employing grid-modulated cold cathode source having nanotube emitters

We describe an ultra-small structure that produces visible light of varying frequency, from a single metallic layer. In one example, a row of metallic posts are etched or plated on a substrate according to a particular geometry. When a charged particle beam passed close by the row of posts, the posts and cavities between them cooperate to resonate and produce radiation in the visible spectrum (or even higher). A plurality of such rows of different geometries can be etched or plated from a single metal layer such that the charged particle beam will yield different visible light frequencies (i.e., different colors) using different ones of the rows.

Electron beam induced resonance

We describe an ultra-small resonant structure that produces electromagnetic radiation (e.g., visible light) at selected frequencies. The resonant structure can be produced from any conducting material (e.g., metal such as silver or gold). In one example, a number of rows of posts are etched or plated on a substrate, with each row having a particular geometry associated with the posts and cavities between the posts. A charged particle beam is selectively directed close by one of the rows of posts, causing them to resonate and produce radiation (e.g., in the visible spectrum at a predominant frequency). Directing the charged particle beam at a different row yields radiation at a different predominant frequency.

Selectable frequency light emitter

A compact device called the split cavity modulator whose self-generated oscillating electromagnetic field converts a steady particle beam into a modulated particle beam. The particle beam experiences both signs of the oscillating electric field during the transit through the split cavity modulator. The modulated particle beam can then be used to generate microwaves at that frequency and through the use of extractors, high efficiency extraction of microwave power is enabled. The modulated beam and the microwave frequency can be varied by the placement of resistive wires at nodes of oscillation within the cavity. The short beam travel length through the cavity permit higher currents because both space charge and pinching limitations are reduced. The need for an applied magnetic field to control the beam has been eliminated.

Method and split cavity oscillator/modulator to generate pulsed particle beams and electromagnetic fields

When using micro-resonant structures, a resonant structure may be turned on or off (e.g., when a display element is turned on or off in response to a changing image or when a communications switch is turned on or off to send data different data bits). Rather than turning the charged particle beam on and off, the beam may be moved to a position that does not excite the resonant structure, thereby turning off the resonant structure without having to turn off the charged particle beam. In one such embodiment, at least one deflector is placed between a source of charged particles and the resonant structure(s) to be excited. When the resonant structure is to be turned on (i.e., excited), the at least one deflector allows the beam to pass by undeflected. When the resonant structure is to be turned off, the at least one deflector deflects the beam away from the resonant structure by an amount sufficient to prevent the resonant structure from becoming excited.

Switching micro-resonant structures by modulating a beam of charged particles

A device for generating RF energy from electromagnetic radiation of another form, such as light, includes an emitter responsive to the electromagnetic radiation for producing a beam of charged particles, an electrode spaced from the emitter to define a path for the charged particles, and a resonant structure for supporting RF oscillations and disposed with respect to the path to enable energy transfer between the charged particles and an RF field associated with the RF oscillations. When biased, the devices operate in a multi-pass mode, wherein the charged particles undergo multiple oscillations while remaining in phase with the RF field. When unbiased, the devices operate in a half-cycle mode to produce RF oscillations with no externally applied input power other than the electromagnetic radiation.

Jr. John W. Freeman

Papers

Device for generating RF energy from electromagnetic radiation of another form such as light