| 释义 |
plasma|ˈplæzmə|
[Late and eccl. L. plasma a thing formed or moulded, an image, a. Gr. πλάσµα, fr. πλάσσειν to form, mould.]
†1. Form, mould, shape. Obs. rare.
1712H. More's Antid. Ath. i. v. §3 schol., They act upon the Matter and form it into this or that Plasma or Fashion. 1824–9Landor Imag. Conv., Southey & Porson ii. Wks. 1846 I. 83/2 A great portion of his compositions is not poetry, but only the plasma or matrix of poetry. Ibid. Alfieri & Salomon 190/1 We Italians sometimes fall into what..you may call the plasma of witticism, by mere mistake, and against our genius.
2. A subtranslucent green variety of quartz, allied to chalcedony and heliotrope, anciently used for ornaments.
1772tr. Cronstedt's Min. 81 Plasma or mother of the emerald. 1839Ure Dict. Arts 208 Under it [calcedony] may be grouped..chrysoprase, plasma,..and sard. 1861C. W. King Ant. Gems (1866) 14 Plasma..sometimes written Prasma..is merely Calcedony coloured green by some metallic oxide, probably copper or nickel. 1864― Gnostics 76 This amulet, which is always cut in Plasma, the Jasper par excellence of the ancients.
attrib.1900A. S. Murray in Brit. Mus. Ret. 64 Green plasma scaraboid, with intaglio of a warrior.
3. Phys. The colourless coagulable liquid part of blood, lymph, or milk, in which the corpuscles (or, in milk, oil-globules) float; also, the similar liquid obtained from fresh muscle.
1845G. E. Day tr. Simon's Anim. Chem. I. 114 The plasma of living blood exists as a clear fluid, in which the corpuscles are seen to float. 1855Holden Hum. Osteol. (1878) 19 The nutrient fluid, or ‘plasma’ of the blood. 1873C. H. Ralfe Phys. Chem. 118 The muscular plasma is obtained by injecting the muscles of a freshly killed animal with a 1 per cent solution of sodium chloride. 1876tr. Wagner's Gen. Pathol. (ed. 6) 230 Normal lymph consists of a colorless plasma and lymph-corpuscles. 1895in Syd. Soc. Lex.
4. Biol. = plasm 4.
1864Webster, Plasma..2. (Physiol.) The viscous material of a cell from which the new developments take place. 1867J. Hogg Microsc. i. iii. 223 For certain delicate organisms, as the Desmidaceae and Diatomaceae, whose plasma may be affected by too dense a medium. 1872Beale Bioplasm i. §14 As the germ of every living thing consists of matter having the wonderful properties already mentioned, I have called it germinal matter; but the most convenient and least objectionable name for it is living plasma or bioplasm. 1876Lankester tr. Haeckel's Hist. Creat. I. 185 The entire body..consists..of shapeless plasma, or protoplasm.
5. Pharm. A name for glycerite or starch.
1890in Cent. Dict. 1895in Syd. Soc. Lex.
6. Physics. A gas in which there are positive ions and free negative electrons, usu. in approximately equal numbers throughout and therefore electrically neutral; esp. one exhibiting phenomena due to the collective interaction of the charges. Also, any analogous collection of charged particles in which one or both kinds are mobile, as the conduction electrons in a metal or the ions in a salt solution.
Electrical neutrality and collective phenomena are often made necessary characteristics of a plasma (e.g. quot. 19672).
1928I. Langmuir in Proc. Nat. Acad. Sci. XIV. 628 It seemed that these oscillations must be regarded as compressional electric waves somewhat analogous to sound waves. Except near the electrodes..the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is very small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons. 1930Physical Rev. XXXVII. 1467 The plasma used in this investigation was the positive column of a mercury arc. 1941Millman & Seely Electronics x. 307 The largest portion of a glow discharge is the plasma. Ibid. 309 In addition to the electrons and ions that exist in equal concentrations, a plasma contains many gas molecules. 1958Engineering 31 Jan. 134/2 The stable plasma reaches the high temperatures, of the order of 5 million deg. K., necessary for producing thermonuclear reactions. 1960Soviet Physics Doklady V. 363 At a distance from the earth of 4 earth radii, a plasma with a temperature of not more than tens of thousands of degrees was detected. 1966McGraw-Hill Encycl. Sci. & Technol. X. 386/1 If the over-all dimensions of a region containing a plasma are small compared to λD, only simple collisional or single-particle behavior is to be expected, the plasma will behave as an ordinary low-density gas, and collective processes will not be important. 1967L. K. Branson Introd. Electronics ix. 315 The plasma consists of a mixture of positive, negative, and neutral particles and ..in any given volume-element there are equal numbers of ions and electrons. Further, the plasma..fills the entire volume between anode and cathode except for a narrow region at the cathode called the sheath. 1967Condon & Odishaw Handbk. Physics (ed. 2) iv. xi. 188/1 The phenomena that occur in a plasma and distinguish it from any arbitrary collection of charged particles are the near equality of positive and negative charges throughout the plasma volume and the ability of the charges to participate in plasma oscillations. 1969Steele & Vural Wave Interactions in Solid State Plasmas i. 4 In a metal like copper, the free electrons comprising the plasma are electrically compensated by the positively ionized copper atoms. 1971E. Nasser Fundamentals of Gaseous Ionization & Plasma Electronics xiv. 427 Liquid plasmas exist in salt solutions where the positive and negative ions move separately. 1974R. C. Davidson Theory of Nonneutral Plasmas p. xi, Nonneutral plasmas exhibit collective properties that are qualitatively similar to those of neutral plasmas. For example, in klystrons and traveling-wave tubes, the collective oscillations necessary for microwave generation and amplification are excited even under conditions in which the electron beams..are unneutralized. 1974Nature 5 Apr. 494/2 In a cold plasma (which is a good approximation for most of the magnetosphere away from the equatorial region) there are two wave modes. 1976T. Beer Aerospace Environment i. 16 The solar wind is a plasma of hydrogen ions (protons) and electrons travelling at speeds that range from 300 km s–1 to 1000 km s–1, depending on solar activity.
7. Soil Sci. (See quots.)
1958I. W. Cornwall Soils for Archaeologist xvii. 190 Intergranular spaces and conducting channels may be filled, or partly filled, with colloids and precipitates, conveyed and deposited..by percolating moisture. This is the soil-plasma, which constitutes in part the cement between adjacent grains and in part mere filling of available voids. 1976Courtney & Trudgill Soil ii. 17/2 In thin sections under a microscope the soil plasma can be recognized... It is an amorphous combination of humus, clays and chemical compounds (e.g. iron oxide), and is produced by the secondary weathering processes..and by the incorporation of organic matter. Ibid., The presence of mineral matter in the plasma distinguishes it from the overlying purely organic horizons.
8. a. attrib., as plasma cloud; plasma arc, a very hot plasma jet produced by passing a noble gas through a nozzle that is one electrode of an electric arc, used in plasma torches; plasma-corpuscle, name given to a type of cell found in connective tissue; plasma-current, -layer, -zone = plasmatic current, etc.; plasma dynamics (also as one word), the science of the dynamical properties and behaviour of gaseous plasmas; so plasma-dynamic, -dynamical adjs.; plasma engine, a form of jet engine that produces and ejects plasma; plasma frequency, the natural resonant frequency of a plasma oscillation, which is also the minimum frequency of electro-magnetic waves that can travel through the plasma without attenuation and is approximately 8920 √n Hz, where n is the number of free electrons per cc.; plasma jet, a high-speed stream of plasma (ionized gas) ejected from a plasma engine or plasma torch; plasma membrane Biol. = plasmalemma; also, a similar membrane around an intracytoplasmic vacuole; plasma oscillation, a collective oscillation of the electrons in a plasma; plasma physics, the physics of plasmas such as ionized gases; hence plasma physicist; plasma probe, any device that is inserted or immersed in an ionized gas to investigate its physical properties; plasma propulsion, propulsion of a vehicle by means of a plasma engine; plasma sheath, a thin layer of space charge covering a surface in an ionized gas; plasma torch, a small device that produces a very hot plasma jet for use in cutting solids or coating them with refractory material.
1958Iron Age 4 Dec. 136/1 Thanks to the development of the new *plasma arc torch, a brand new method for fabricating shapes and applying ultra-high-temperature coatings is now a reality. 1963H. R. Clauser Encycl. Engin. Materials & Processes 480/2 The cost of depositing the high-melting-point coatings with the plasma-arc process is comparable with that of the flame-sprayed coatings. 1973Materials & Technol. VI. i. 60 A number of unconventional methods of cutting wood have been examined, largely with the object of reducing waste. These include the use of the plasma arc, which produces very high temperatures with a nozzle of very small diameter.
1869Kirby in Q. Jrnl. Microsc. Sci. IX. 31 Naked *Plasma-bodies without nuclei.
1960Aeroplane XCVIII. 610/1 It appears that *plasma clouds emitted from the Sun run up against the Earth's magnetic field, causing it to release previously trapped particles into the atmosphere. 1967M. Kenyon Whole Hog xviii. 181 Along comes space which everyone had thought was empty, a void, but it turns out it's not, it's filled with radiation belts and plasma clouds and solar winds. 1969Monthly Not. R. Astron. Soc. CXLV. 328 In the Ryle-Longair model, plasma clouds formed by a strong explosion within a galaxy expand..until their dimensions exceed galactic dimensions, at which time they are ejected from the parent galaxy and henceforth evolve independently.
1964E. Stuhlinger Ion Propulsion vi. 277 The heat energy absorbed by the coolant in the reactor may be used to heat..the plasma in a *plasmadynamic converter, or the working fluid in a thermodynamic converter.
1959Astrophysical Jrnl. CXXIX. 217 We are interested in the distance in which a stream of tenuous plasma, directed against another oppositely moving stream of tenuous plasma, is brought to rest as a consequence of *plasma dynamical interaction.
1960Aeroplane XCIX. 837/2 Such subjects as magneto⁓hydrodynamics, MHD mechanics, and *plasmadynamics. 1970New Scientist 5 Feb. 273/2 Plasma dynamics is a subject with applications in many branches of physics and technology..—space physics and the quest for thermo⁓nuclear fusion being but two examples.
1958S.A.E. Jrnl. Apr. 93/2 Another phase of our investigations..is the development of a *plasma engine, in which small amounts of plasma are ejected at extremely high velocities. 1967Electronics 6 Mar. 8/2 He directed work on plasma engines and space suits. 1974Hawkey & Bingham Wild Card xv. 131 The propulsion pack was okay for the demonstration... We plan to replace it with a small plasma engine.
[1929Physical Rev. XXXIII. 198 Thus the lower frequency limit for long waves coincides with the plasma-electron frequency.] 1949Ibid. LXXV. 1852/1 For a typical density of 1012 electrons per cm3, the *plasma frequency is about 1010 c.p.s. 1964D. B. Newman Space Vehicle Electronics iv. 225 Above the plasma frequency the plasma has dielectric properties... Well below the plasma frequency, the plasma acts like a conductor. 1971Ferry & Fannin Physical Electronics vii. 96 For a metal, where the electron concentration is about 1028 m–3, the plasma frequency is found to be about 5·6 ×1015 Hz, or in the ultraviolet region.
1957G. M. Giannini Plasma Jet & its Applications (U.S.A.F. Office Scientific Res. Techn. Note 57–520) 22 The ‘*plasma jet’ can be used for many of the purposes described... The jet is very hot, highly ionized, has a high velocity. 1960Aeroplane XCVIII. 610/2 Because of the low thrust produced, the plasmajet cannot be employed for rocket-launching from Earth. It must be carried into orbit by a more powerful chemical rocket and started in the weightless environment of space. 1964Sci. News Let. 12 Sept. 163 Plasma jets, the white-hot streams of gas used for such tasks as cutting and welding, may soon have yet another use, ‘steering’ satellites through space. 1972D. G. Shepherd Aerospace Propulsion viii. 202 The arc jet or plasma jet utilizes the very high temperatures in arcs to heat the propellant.
1876tr. Wagner's Gen. Pathol. (ed. 6) 178 The *plasma-layer..disappears in the smaller arteries and veins.
1900Ann. Bot. XIV. 352 The entire structure, antheridium, tube, and oogonium, have in reality become for a time a single cell bounded by a single continuous *plasma-membrane. 1922W. Stiles in New Phytologist XXI. 141 The term plasma-membrane will be used to denote a surface layer of protoplasm which behaves as a membrane surrounding the bulk of the protoplasm, and which may exhibit different degrees of permeability to different substances... The membrane bounding the outside of the protoplast, and so in contact with the cell wall, will be called the external plasma-membrane, and that bounding the vacuole, the internal plasma-membrane. 1948New Biol. V. 40 The plasma membrane is highly permeable to substances which are soluble in fats and in fat solvents. 1965Bell & Coombe tr. Strasburger's Textbk. Bot. 13 The inner plasma membrane surrounding the vacuole is known as the tonoplast, and that adjacent to the cell wall as the plasmalemma. 1968R. Rieger et al. Gloss. Genetics & Cytogenetics 341 In some cells (bacteria, plants), a cell wall..is universally recognized as a structure separate from the plasma membrane. 1970Ambrose & Easty Cell Biol. viii. 258 The outer cell membrane, or plasma membrane (sometimes known as the cell membrane, or plasmalemma), has a unique role, since the cell interacts with its environment through it.
1928I. Langmuir in Proc. Nat. Acad. Sci. XIV. 629 *Plasma Oscillations.—If..we change the concentration of electrons by some transient external means, the resulting electric fields act..to equalize the concentration, but the potential energy of these fields is converted into kinetic energy of the electrons so that oscillations occur, and electric waves may result. 1970W. A. Harrison Solid State Theory iii. 288 Physically these plasma oscillations correspond to soundlike compression waves in the electron gas. 1972Akasofu & Chapman Solar-Terrestrial Physics vii. 472 While the plasma cloud is streaming through the solar atmosphere it induces plasma oscillations there. These oscillations are observed at the earth as a Type II radio burst.
1968New Scientist 24 Oct. 186 To bring about nuclear fusion..plasma with a density of 1014 nuclei per cu. cm. must be held together for about one second. To bring this about is the dream of *plasma physicists. 1976T. Beer Aerospace Environment i. 2 The plasma physicist can use the Earth's upper atmosphere as a gigantic laboratory to study the behaviour of a large⁓scale plasma being acted upon by the Earth's magnetic field.
1958C. C. Adams Space Flight 345 Some scientists think that controlled fusion may be with us in 20 years or so, and if so we may completely bypass fission... Work in *plasma physics will have to be carefully watched, and it is through research in this area that eventual success is expected. 1963Wall St. Jrnl. 22 Jan., Kirtland researchers are delving into plasma physics—the study of partially ionized gases—to determine to what extent high-level nuclear blasts are likely to disrupt vital communications. 1970G. K. Woodgate Elem. Atomic Structure i. 3 Quantitative calculations of the behaviour of free atoms are required for the less well-defined fields..of, for example, solid-state physics, plasma physics, and..astrophysics.
1961Flight LXXIX. 462/2 Valuable information had been transmitted from the rubidium vapour magnetometer, two fluxgate magnetometers and the *plasma probe. 1965K. W. Gatland Spacecraft & Boosters II. 87/2 The radio⁓frequency plasma probe consisted of a pair of grid-like electrodes through which a radio-frequency electric field was applied to a small region near the satellite. 1977Sci. Amer. Mar. 39/3 The first data available from the Ames Research Centre's plasma probe on Pioneer 10 as it traversed interplanetary space were the hourly values of the speed of the [solar] wind.
1958C. C. Adams Space Flight 54 A new Astronautics Research Laboratory with propulsion, astrophysical, and materials sections to study very high-energy fuels, including *plasma propulsion systems. 1969Boyd & Sanderson Plasma Dynamics v. 107 Space research has given a great impetus to the development of plasma propulsion since it has important potential advantages over conventional propellants, especially for long-range missions.
1961Aeroplane C. 462/2 During hypersonic flight on the return from orbit, an ionized ‘*plasma sheath’ will envelop the glider, impeding the reception and transmission of radio signals. 1969M. A. Kasha Ionosphere iii. 48 A spacecraft is generally surrounded by some form of plasma sheath. This means that it is very difficult to measure..the electrical potential of the space plasma.
1959Welding Engineer Feb. 50/2 Two 600-amp units power a 50-kw *plasma torch, and voltage requirements are being set by the gas being used. 1961Jrnl. Appl. Physics XXXII. 821/1 This article describes a plasma torch based on inductive coupling to an ionized gas... Conventional plasma torches require electrodes to carry energy to the gas. 1968Observer 22 Dec. 4/5 The plasma torch, another torch device in industrial use, can virtually disintegrate material at a temperature of 36,000 degrees C.
b. Used attrib. to designate (the concentration of) substances in blood plasma.
1891W. D. Halliburton Text-bk. Chem. Physiol. & Path. xv. 238 The globulin pre-existent in the blood plasma..may be termed plasma-globulin. 1927[see plasmapheresis]. 1941Amer. Jrnl. Path. XVII. 360 The question whether increase of the plasma protein concentration would protect against heavy metal poisoning. 1956Nature 4 Feb. 238/1 The amino-acid pattern of the urine from this cystinuric dog is.., apart from threonine, identical with that found in cases of human cystinuria, while the finding of a low plasma-cystine points to a similar etiology. 1961Lancet 22 July 171/2 Because of the diurnal variation in plasma-cortisol (hydrocortisone) concentration, all blood samples were drawn between 9 a.m. and 10 a.m. 1969E. Kelemen Physiopath. & Therapy Human Blood Dis. i. 105 About 80–90% of plasma proteins, i.e. fibrinogen, albumin, and certain globulins, including most of the plasma coagulation factors, are formed in the liver. 1975J. W. Linman Hematol. v. 183/1 Plasma fibrinogen is increased in persons with valvular prostheses or homografts.
Add:[8.] [a.] plasma diagnostics (const. as sing.), the determination of the physical characteristics of plasmas by experimental methods that do not significantly alter them.
1961IRE Trans. Antennas & Propagation IX. 317/1 (heading) The potential utility of scanning microwave beams in *plasma diagnostics. 1981Nature 1 Oct. 338 Plasma diagnostics using high-resolution X-ray spectroscopy is a field of expanding importance in both fusion reactor research and high-energy astrophysics.
▸ attrib. Designating a flat display screen which uses an array of cells containing an inert gas such as neon which emits ultraviolet radiation when ionized to form a plasma, causing visible light of an appropriate colour to be emitted separately for each cell of the screen, according to the image being displayed. Esp. in plasma display, plasma screen.
1966D. L. Bitzer & H. G. Slottow in Proc. AFIPS Conf. 29 541/1 The Plasma Display is a new device that, in contrast to the cathode ray tube, retains its own images and responds directly to the digital signals from the computer. 1978SIAM Rev. 20 434 The coefficients generated..were used on the plato computer to represent various orbits on a plasma screen. 1993Sci. Amer. Mar. 41 The three technologies that have achieved some market acceptance—plasma panels, electroluminescent displays and liquid-crystal displays—all fall short in one or another of these respects. 2000Daily Tel. 16 Mar. (Connected section) 10/3 Crowding a large group of students around a 15in PC monitor or even a large-screen TV is not easy, but flat-screen plasma displays provide plenty of viewing space. |