electro-, electr-, electri-

1. The process of using a focused beam of electrons to heat materials to the fusion point.
2. A process in which a welder generates a stream of electrons traveling at up to 60 percent of the speed of light as it focuses the beam to a small, precisely controlled spot in a vacuum, and converts the kinetic energy into an extremely high temperature on impact with the piece being worked on.
3. A welding process which takes place in a vacuum.

Heat is produced by a focused electron beam that can produce welds having depth-to-width ratios of up to twenty to one.

Applications include welding of thin metal foils to thicker metal without burning, sealing of metal cans containing uranium fuel elements for reactors, and direct fusion welding of ceramic objects.

An amplifier consisting of an electron-gun modulation system, semiconductor target and output coupling network all within a glass or ceramic envelope.

The semiconductor target is a pair of silicon diodes, each consisting of two metallic electrodes with a pn (positive-negative) junction under the top contact.

A pn junction or a diode (one way valve) is a pn junction with p-type (positive-type) on one side and n-type (negative-type) on the other side.

When a positive voltage is applied to the p-type side (forward bias), it shrinks and overcomes the depletion zone, causing the current to flow from the p-type to the n-type side. When a negative voltage is applied to the p-type of the diode (reverse bias), it increases the depletion zone and prevents current from flowing.

The amplifier operation is based on the fact that a modulated electron beam can control the current in a reverse-based semiconductor junction.

1. A device that generates alternating current.

It is characterized by a circuitry that feeds a portion of the generated energy back into the system to sustain its operation, and by an electron stream that is coupled between the screen and the plate to reduce the effects of the load.

2. An oscillator employing a multigrid tube in which the cathode and two grids operate as a conventional oscillator and the electron couples the plate-circuit load to the oscillator.

The anode-circuit load is coupled to the oscillator through the electron stream.

1. In electron microscopy, having a density that prevents penetration by electrons.
2. Characterized by being relatively opaque to the passage of the electron beam in an electron microscope.

Such an object will appear as a dark area on the viewing screen and photographic prints.

1. A contoured representation of electron density at various points in a crystal structure expressed in electrons per cubic angstrom with the highest near atomic centers.

The map is calculated using a Fourier synthesis, a summation of waves of known phase, frequency, and amplitude.

2. A three-dimensional representation of the electron density of a molecular structure based on x-ray diffraction data.

1. The study of crystal structure by electron-diffraction methods.
2. The diffraction of electrons when they pass through crystalline matter, useful in the study of the structure of materials.
3. An examination of solid surfaces by observing the diffraction of a stream of electrons on the surfaces.

A diffraction is the bending or spreading out of waves; such as, of sound or light, as they pass around the edge of an obstacle or through a narrow opening as when light passes sharp edges or goes through narrow slits and the rays are deflected and produce fringes of light and dark bands.

1. A camera used to obtain a photographic record of the position and intensity of diffracted beams which may be produced when a specimen is irradiated by a beam of electrons.
2. A special evacuated camera equipped with the means for holding a specimen and bombarding it with a sharply focused beam of electrons.

A cylindrical film placed around a specimen and which records the electrons that might be scattered or diffracted by it.

1. The process of machining which is performed by electric sparks in a non-conductive liquid intervening substance.
2. A process by which materials that conduct electricity can be removed from a metal by an electric spark.

It is used to form holes with different shapes in materials that have poor machine operations.

1. A curved line on a graph that shows the electron distribution in a solid at different energy levels.
2. A curve or line indicating the electron distribution in the different available energy levels of a solid substance.

1. Charged with negative electricity: The electronegative situations result in the attraction of positively charged material and the repulsion of negatively charged ones.
2. Having the power to attract electrons: Something is likely to become negatively charged when it is combined with a less electronegative matter.

Nonmetals like glass and wooden objects are considered to be electronegative materials.

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two-types of electric charge; positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract.

An atom that readily accepts electrons and so has a tendency to acquire a partial negative charge in a covalent bond (a chemical bond between two atoms in which electrons are shared between the two nuclei) or to form a negative ion.

A developer containing negatively charged toner particles.

1. An electrode's potential stated as negative in relation to the standard potential of the hydrogen electrode that is established at zero.
2. The difference in an electrical charge between two points in a circuit expressed in volts of an electrode or as negative with respect to the hydrogen electrode.

The power of an atom in a molecule to attract electrons to itself.

1. A numerical expression of the relative negativity of various substances, based on calculations that use bond energies and which assign a value of four to fluorine, the most electronegative element.

A system proposed by Linus Carl Pauling (1901–1994).

2. A numerical scale of electronegativities that are based on bond-energy calculations for different elements joined by covalent bonds.