An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 8 Search : barrier
barrier
  ورغه   
varqé (#)

Fr.: barrière   

General: Anything that prevents passage or blocks.
Physics: 1) A region where the potential energy is greater than the total energy of a particle, whereby the particle cannot go through.
2) The depletion layer of a P-N junction in a diode.

O.F. barrière "obstacle," from V.L. *barraria, from *barra "bar, barrier."

Varqé, from varq "a mound, a dam" + nuance suffix. Varq is probably related to Av. vâra- "barrage," vara- "enclosure," var- "castle," Mid.Pers. var "enclosure," from Av. root var- "to cover, to conceal;" variants: barq (Torbat Heydariyei), valgâ (štiyâni), var (Qomi); cf. Skt. vatra- "a dike, a dam,"varana- "rampart, wall," from vr- "to obstruct, close, cover, hide; to choose."

Coulomb barrier
  ورغه‌ی ِ کولن   
varqe-ye Coulomb (#)

Fr.: barrière de Coulomb   

The energy barrier due to electrostatic interaction that two nuclei (for example two protons) need to overcome so they can get close enough to undergo nuclear fusion (to form a helium).

coulomb; → barrier.

Gamow barrier
  ورغه‌ی ِ گاموف   
varqe-ye Gâmof (#)

Fr.: barrière de Gamow   

In nuclear physics, a potential barrier near the surface of the nucleus that inhibits the release of alpha particles.

Gamow, after George Gamow (originally Georgiy Antonovich Gamov), the Ukrainian born theoretical physicist and cosmologist, who discovered quantum tunneling; → barrier.

nuclear barrier
  ورغه‌ی ِ هسته‌ای   
varqe-ye haste-yi (#)

Fr.: barrière nucléaire   

The region of high potential energy through which a charged particle must pass on entering or leaving an atomic nucleus. → Gamow barrier.

nuclear; → barrier.

potential barrier
  ورغه‌ی ِ توند   
varqeye tavand

Fr.: barrière de potentiel   

Region in a field of force in which the potential is such that a particle, which is subject to the field, encounters opposition to its passage.

potential; → barrier.

Schottky barrier
  ورغه‌ی ِ شوتکی   
varqe-ye Schottky

Fr.: barrière de Schottky   

A junction between a metal and a semiconductor, which exhibits rectifying characteristics. A Schottky barrier has a very fast switching action and low forward voltage drop of about 0.3 volts, compared with 0.6 volts in silicon diodes, which use adjacent p-type and n-type semiconductors.

Named after Walter Hans Schottky (1886-1976), German physicist, who described the phenomenon; → barrier.

Schwarzschild barrier
  ورغه‌ی ِ شو‌آرتسشیلد   
varqe-ye Schwarzschild

Fr.: barrière de Schwarzschild   

An upper theoretical limit to the → eccentricity of orbits near a → supermassive black hole (SBH). It results from the impact of → relativistic precession on the stellar orbits. This phenomenon acts in such a way as to "repel" inspiralling bodies from the eccentric orbits that would otherwise lead to capture as → extreme mass ratio inspiral (EMRI)s. In other words, the presence of the Schwarzschild barrier reduces the frequency of EMRI events, in contrast to that predicted from → resonant relaxation. Resonant relaxation relies on the orbits having commensurate radial and azimuthal frequencies, so they remain in fixed planes over multiple orbits. In the strong-field potential of a massive object, orbits are no longer Keplerian but undergo significant perihelion precession. Resonant relaxation is only efficient in the regime where precession is negligible. The Schwarzschild barrier refers to the boundary between orbits with and without significant precession. Inside this point resonant relaxation is strongly quenched, potentially reducing inspiral rates.

Schwarzschild black hole; → barrier.

sound barrier
  دیوار ِ صدا، ورغه‌ی ِ ~   
divâr-e sedâ, varqe-ye ~

Fr.: mur du son   

A sharp increase in aerodynamic drag that occurs as the speed of an aircraft approaches the speed of sound. Also called sonic barrier.

sound; → barrier.