One use is to detect bone loss in the spine and hips.
2. A stream of electrons, or electricity, that is directed towards a receiving object.
3. A narrow stream of electrons moving in the same direction, all having about the same velocity.
The electron beam of the super-microscope has become a basic tool in the research of diseases.
2. A device used in atomic physics to produce highly charged ions by bombarding atoms with a powerful electron beam.
3. The technique of transporting high-energy, high-current electron beams from an accelerator to a target through a region of high-pressure gas by creating a path through the gas where the gas density may be temporarily reduced.
The gas may be ionized; or a current may flow whose magnetic field focuses the electron beam on the target.
2. Velocity-modulated generator, such as a klystron tube (type of vacuum tube used as an amplifier), used to generate extremely high radio frequencies.
A klystron is an evacuated electron-beam tube in which an initial velocity modulation imparted to electrons in the beam results subsequently in density modulation of the beam. A klystron is used either as an amplifier in the microwave region or as an oscillator.
2. Drilling of tiny holes in a ferrite, semiconductor, or other material by using a sharply focused electron beam to melt and evaporate or sublimate the material in a vacuum.
2. An electronic transducer, either fixed or adjustable, that reduces the amplitude of a wave without causing significant distortion.
Electron beam evaporation is a commonly used process for coating lenses and filters with anti-reflection, scratch-resistant or other specialized coatings.
The process is also commonly used for coating insulating and resistor films on electronic components.
2. The use of intense beams of electrons to implode small pellets of deuterium and tritium so that they reach the temperature and density required for initiating a fusion reaction.
It consists of an emitting cathode and an anode, with an aperture for passage of some of the electrons.
Usually the beam is made to strike a fluorescent screen so the deflection can be observed.
2. A source of multiple charged heavy ions which uses an intense electron beam with energies of five to ten kiloelectronvolts to successively ionize injected gas.
The resulting laser output beam moves correspondingly, to provide high-speed scanning for data retrieval and imaging applications.
The beam can be electronically blanked, unblanked, or modulated with analog video signals for the projection of picture or other graphic data.
2. The practice of scanning a beam of electrons in a patterned fashion across a surface covered with a film called the resist, exposing the resist, and of selectively removing either exposed or non-exposed regions of the resist called, "developing".
3. Lithography in which the radiation-sensitive film or resist is placed in the vacuum chamber of a scanning-beam electron microscope and exposed by an electron beam under digital computer control.
After exposure, the film is removed from the vacuum chamber for conventional development and other production processes.
2. A machining process which takes place in a vacuum.
Heat is produced by a focused and controlled electron beam at a sufficiently high temperature to volatilize and so to remove metal in a specified manner.
Drilling and cutting are examples of specific applications.
2. An instrument which measures the intensity and direction of magnetic forces by the immersion of an electron beam into the magnetic field.
It's used principally for refining metals to a higher degree of purity than is possible with conventional vacuum-melting techniques.
Its chief advantage is the ability to control the temperature of the molten material and the time it remains melted because both affect the degree of volatilization of impurities.
Volatilization is the conversion of a chemical substance from a liquid or solid state to a gaseous or vapor state by the application of heat, by reducing pressure, or by a combination of these processes. It is also known as vaporization.
2. A parametric amplifier in which energy is pumped from an electrostatic field into a beam of electrons traveling down the length of the tube, and electron couplers impress the input signal at one end of the tube and translate spiraling electron motion into electric output at the other end.
2. The use of an electron beam to produce excitation for population inversion and lasing action in a semiconductor laser.
2. A recorder in which a moving electron beam is used to record signals or data on to photographic or thermoplastic film in a vacuum chamber.
3. A device that transfers computer data onto microfilm using an electron beam.
2. An electron tube whose performance depends on the formation and control of one or more electron beams.
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.
2. A stream of electrons, emitted by a single source, which move in the same direction, and at the same speed.
3. A stream of electrons which can "write" on phosphor surfaces; such as, a CRT screen expose photoresistent-coated semiconductor wafers by direct writing or exposure through a mask, or magnify objects by passing through magnetic "lenses".
It can also be a cutting tool.
A cathode-ray tube, or CRT, produces images when its phosphorescent surface is struck by electron beams.
2. Use of a high-velocity ion beam to remove material from a surface.
2. A system that prevents an ion spot from forming on a cathode-ray tube screen, generally by using a magnetic field to divert the beam. 3. An arrangement whereby ions in the electron beam of a cathode-ray tube are prevented from bombarding (hitting with high-energy particles) the screen and producing an ion spot, usually employing a magnet to bend the electron beam so that it passes through the tiny aperture of the electron gun, while the heavier ions are less affected by the magnetic field and are trapped inside the gun.
A metal electrode, usually of titanium, into which ions from an ion pump are attracted or absorbed.
Static electric fields cannot separate ions by their mass but do separate them by their energy and so provide an important design element by functioning as an energy filter.
The beam removes atoms from the workpiece by transferring energy and momentum to atoms on the surface of the object.
When an atom strikes a cluster of atoms on the workpiece, it dislodges between 0.1 and 10 atoms from the workpiece material.
Ion-beam machining, IBM, permits the accurate machining of virtually any material and is used in the semiconductor industry and in the manufacture of aspheric lenses.
The technique is also used for texturing surfaces to enhance bonding, for producing atomically clean surfaces on devices; such as, laser mirrors, and for modifying the thickness of thin films and membranes.
2. A process in which bombardment of a solid with a beam of energetic ions causes the intermixing of atoms of two separate phases originally present in the near-surface region.
2. The process by which the mass spectrum of an ion beam is analyzed, generally by altering the electric or magnetic fields or by moving a probe in a mass spectrometer.
Proton therapy's promise lies in its ability to destroy cancerous cells while sparing healthy cells half a millimeter away, reducing side effects. It also allows doctors to ramp up the radiation dose, theoretically improving cure rates.
The precise targeting is possible because the subatomic particles release the bulk of their destructive energy beneath the skin, at the tumor's depth, rather than near the surface, as X-rays do; and while standard radiation tends to cause damage to healthy tissues on the far side of tumor, protons slow and stop as they release their energy pulse, eliminating a harmful exit dose.2. A precise form of radiation treatment for cancer and other conditions.
It is said to minimize damage to healthy tissue and surrounding organs, and such proton treatment is considered to be highly successful and it results in fewer side effects.