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krypton    音标拼音: [kr'ɪptɑn]
n. 氪

氪

krypton
n 1: a colorless element that is one of the six inert gasses;
occurs in trace amounts in air [synonym: {krypton}, {Kr},
{atomic number 36}]

Noble \No"ble\, a. [Compar. {Nobler}; superl. {Noblest}.] [F.
noble, fr. L. nobilis that can be or is known, well known,
famous, highborn, noble, fr. noscere to know. See {know}.]
1. Possessing eminence, elevation, dignity, etc.; above
whatever is low, mean, degrading, or dishonorable;
magnanimous; as, a noble nature or action; a noble heart.
[1913 Webster]

Statues, with winding ivy crowned, belong
To nobler poets for a nobler song. --Dryden.
[1913 Webster]

2. Grand; stately; magnificent; splendid; as, a noble
edifice.
[1913 Webster]

3. Of exalted rank; of or pertaining to the nobility;
distinguished from the masses by birth, station, or title;
highborn; as, noble blood; a noble personage.
[1913 Webster]

Note: Noble is used in the formation of self-explaining
compounds; as, noble-born, noble-hearted, noble-minded.
[1913 Webster]

{Noble gas} (Chem.), a gaseous element belonging to group
VIII of the periodic table of elements, not combining with
other elements under normal reaction conditions;
specifically, {helium}, {neon}, {argon}, {krypton},
{xenon}, or {radon}; also called {inert gas}.

{Noble metals} (Chem.), silver, gold, and platinum; -- so
called from their resistance to oxidation by air and to
dissolution by acids. Copper, mercury, aluminium,
palladium, rhodium, iridium, and osmium are sometimes
included.
[1913 Webster]

Syn: Honorable; worthy; dignified; elevated; exalted;
superior; sublime; great; eminent; illustrious;
renowned; stately; splendid; magnificent; grand;
magnanimous; generous; liberal; free.
[1913 Webster]


Krypton \Kryp"ton\ (kr[i^]p"t[o^]n), n. [NL., fr. Gr. krypto`n,
neut. of krypto`s hidden.] (Chem.)
An inert gaseous element of the argon (noble gas) group, of
atomic number 36, occurring in air to the extent of about one
volume in a million. It was discovered by Ramsay and Travers
in 1898. Boiling point, -152.3[deg] C.; melting point,
-156.6[deg] C.; symbol, Kr; atomic weight, 83.8.
[Webster 1913 Suppl.]

A {frame language}.

["An Essential Hybrid Reasoning System: Knowledge and Symbol
Level Accounts of KRYPTON", R.J. Brachman et al, Proc
IJCAI-85, 1985].

(2011-12-05)


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  • What performance specification would be lower for Krypton than for . . .
    The Starlink satellites, however, will use a different noble gas: krypton It has a lower density, so the satellite fuel tanks need to be larger, and it offers less performance than xenon But krypton can be bought at just one-tenth the cost of xenon, which matters if a company wants to fuel thousands of satellites (emphasis added)
  • spacex - Why will Starlink satellites use krypton instead of xenon for . . .
    To adjust position on orbit, maintain intended altitude, and deorbit, Starlink satellites feature Hall thrusters powered by krypton (emphasis added) Most of the electric propulsion systems that I've heard of use xenon
  • physics - Why might krypton have a lower utilization fraction than . . .
    4 A comment below Why will Starlink satellites use krypton instead of xenon for electric propulsion? links to the 2011 preprint A Performance Comparison of Xenon and KryptonPropellant on an SPT-100 Hall Thruster; IEPC-2011-003 which explains that in this study using a SPT-100 Hall Thruster krypton had a lower utilization fraction than xenon
  • What are the tradeoffs in propellant choices for ion electric based . . .
    Think F = ma, where F in this case is the force of the electric field acting on the ion If you change fuels (say from xenon to krypton, which is lighter), but don't change field strengths, then F stays the same, while m decreases, which means a (acceleration on the ion) must be bigger
  • Does Krypton or Xenon produce more thrust in a Hall-effect thruster . . .
    I am trying to figure out if Xenon or Krypton produces more thrust for a given weight flow rate of fuel when the engine operates at the same discharge voltages The information I find is mixed or I
  • What is the fate of Krypton exhaust from Starlink thrusters?
    If the thrusters have a specific impulse of 1500s, that means the krypton atoms are traveling roughly 15 km s when they exit the nozzle, which exceeds the escape velocity of earth This may or may not be relevant, depending on how dense the atmosphere exosphere is where the thruster is fired, and also depending on which way the thruster is pointed (If the satellite's speed is being
  • ion thruster - Space Exploration Stack Exchange
    Krypton is far more common (~1 ppm, over 10x that of xenon), and is produced with similar strategies, so it is a lot cheaper than xenon, at 290 USD per kilogram SpaceX is launching Starlink very fast, so they can't wait for a suitable xenon supply to show up Xenon is commonly used only because it has a higher performance
  • How much krypton do Starlink satellites carry when they are . . . - spacex
    Starlink satellites use krypton as propellant This answer roughly estimates 2 3 kg of Krypton based on a total delta-V of 190 m s and an exhaust velocity of 20,000 m s But how close is that to re
  • How much krypton is stored on a Starlink satellite?
    How much krypton (fuel) is there for the krypton-powered ion thrusters on Starlink satellites and how long does it last?
  • ion thruster - Space Exploration Stack Exchange
    Xenon and krypton are popular despite their heavy mass because they are simply much easier to put in bottles ionize in the kinds of plasma conditions that are convenient to make on a small spacecraft they are not very reactive with the materials used in the engines





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