| 释义 |
pinch effect
[f. pinch n. + effect n.]
1. Physics. The constriction exhibited by a fluid through which a large electric current is flowing, caused by the attractive force produced by the interaction of the current with its own magnetic field.
[1907E. F. Northrup in Physical Rev. June 474 Some months ago, my friend, Carl Hering, described to me a surprising and apparently new phenomenon which he had observed. He found, in passing a relatively large alternating current through a non-electrolytic, liquid conductor contained in a trough, that the liquid contracted in cross-section and flowed up hill lengthwise of the trough... Mr. Hering suggested the idea that this contraction was probably due to the elastic action of the lines of magnetic force which encircle the conductor... As the action of the forces on the conductor is to squeeze or pinch it, he jocosely called it the ‘pinch phenomenon’. 1907C. Hering in Trans. Amer. Electrochem. Soc. Sept. 331 As the column of liquid looks as though it were being pinched by some mysterious and invisible force, the writer termed it the ‘pinch phenomenon’. Ibid. 337 If to this field there is added another one, I see no reason why it should not add to the pinching effect.] 1911G. H. Clamer in Ibid. XIX. 264 The heavy current..rapidly brings these columns of metal to the liquid condition, and produces therein the ‘pinch’ effect. 1956Sci. News Let. 15 Sept. 174/1 Generating the high heat..requires containers that will not melt or be otherwise affected. Using the ‘pinch effect’ would seem to eliminate the container problem, since the reacting gas column would contract to contain itself, thus not touch any walls. 1958Listener 25 Sept. 454/2 The Americans and Russians independently have developed a principle different from Zeta, although both are working on the Zeta principle of what is known as the pinch effect. 1966McGraw-Hill Encycl. Sci. & Technol. X. 233/1 The force of the pinch effect has..been known to manifest itself by a crushing of tubular conductors exposed to large impulsive currents such as occur in lightning strokes or high-power short circuits. 1972Physics Bull. Feb. 83/2 Flash photolysis features in the Exhibition. Chelsea Instruments is showing its apparatus (based on its Garton flash tube) which utilizes the pinch effect (as in some thermonuclear apparatus) to produce high intensity.
2. The slight narrowing of a record groove caused by the transverse movement of the cutting stylus, resulting in a vertical movement of the stylus at that point during playing.
1935H. C. Bryson Gramophone Record x. 271 Hill and Dale cut records possess great advantages... There is no pinch effect. 1965J. Walton Pick-Ups iii. 40 A mono pick-up (as well as of course the stereo pick-up) should have some vertical compliance and low vertical mass if pinch effect is not to cause damage and excessive ‘needle talk’. 1975G. J. King Audio Handbk. viii. 192 Because the groove is cut by a chisel-shaped tool whose face is at right-angles to the motion of the record, the groove width decreases along the sloping sides of the waveform... This, called ‘pinch effect’, results in vertical oscillation of the replay stylus at a frequency twice that of the modulation and hence in second-harmonic distortion. |