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Topic: Paschen curve

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	GEORGE AUGUSTUS ELIOTT, BARON HEATHFIELD - LoveToKnow Article on GEORGE AUGUSTUS ELIOTT, BARON HEATHFIELD (Site not responding. Last check: 2007-10-20)
		Paschen, and Lummer and Pringsheim verified this relation by observing with a bolometer the intensity at different points in the spectrum produced by a fluorite prism.
		Corresponding ordinates of the curves at different temperatures will therefore vary as the fifth power of the temperature, when the curves are plotted on a wave-length base.
		If the curves were plotted on a frequency base, owing to the change of scale, themaximum ordinates would vary as the cube of the temperature instead of the fifth power, but the form of the function F would remain unaltered.
	76.1911encyclopedia.org /H/HE/HEATHFIELD_GEORGE_AUGUSTUS_ELIOTT_BARON.htm (1623 words)

	Patent 5225855: Electrographic flare reduction by spacing and gas control
		The Paschen curve is a plot of the minimum voltage which must be applied across a gap of thickness, d, filled with a gas at pressure, p, before glow-discharge breakdown will occur.
		A gas having a Paschen curve of less voltage than that for air, like Nitrogen, can be introduced into the gap between the recording head and the spacing means allowing the gas to be present in the gap between the recording medium and the nibline.
		As shown, for the case of a Nitrogen Paschen curve 60, the minimum voltage on curve 60 is approximately 260 volts which is approximately 120 volts less than the minimum voltage of curve 40.
	www.freepatentsonline.com /5225855.html (3985 words)

	Patent 5231048: Microwave energized deposition process wherein the deposition is carried out at a pressure less than ...
		As is known to those of skill in the art the Paschen curve is determined by graphing the minimum voltage required to sustain a plasma of a particular process gas in a particular deposition apparatus at various pressures.
		In a typical Paschen curve it will be noted that as pressure decreases the power or voltage required to sustain the plasma also decreases to a minimum after which the further decrease in the process gas pressure necessitates an increased power or voltage to sustain the plasma.
		Again, the Paschen curve was determined by varying the pressure of the gas mixture in the deposition chamber and noting the minimum power required to sustain a plasma.
	www.freepatentsonline.com /5231048.html (4080 words)

	Definition of hubbert curve
		1:...ubbert]], is the [[derivative]] of the [[logistic curve]].
		The curve was built in response to the difficulty of constr...
		1:...ers and pursuees, and the curve of pursuit is the curve traced by the pursuers.
	www.wordiq.com /search/hubbert+curve.html (825 words)

	Brackett (1922) on his series
		In view of the great intensity of the Paschen lines it is not surprising that many lines were readily observed which under ordinary conditions of excitation would not be detected.
		All atoms which contribute to the radiation of the first Paschen line are left necessarily with the electron in the third orbit, whence it must proceed either to the second or the first orbit unless it is ejected to some orbit of greater quantum number by inelastic collision.
		It should be noticed that the higher members of the Paschen series occur in a region readily studied by photographic methods, plates hypersensitized by means of dicyanin being sensitive to 1.0 µ.
	dbhs.wvusd.k12.ca.us /webdocs/Chem-History/Brackett-1922/Brackett-1922.html (1916 words)

	Remote Sensing Tutorial Page A-7
		Below are two sets of spectral curves, with individual lines noted as downward spikes in part of a Blackbody spectrum (see page 9-2) in the spectral range from 4000-9000 nm (0.4-0.9 µm) range.
		The left curve, for a cool star, shows that the part of the highest part on the curve intersected by the color spread in the Visible spectrum is associated with red, hence such stars are defined colorwise by Red.
		The right curve, for a hot star, has the visible blue at a higher intensity than green or red and hence defines a Blue star (actually, as it appears, such a star is a bright bluish-white).
	rst.gsfc.nasa.gov /Sect20/A7.html (4692 words)

	Copernicus GI Guide: Experiment Description
		Figure 3 shows the calibration curves for both indices and indicates the dependence on spectral type.
		In order to estimate the expected spectrometer count rate for a proposed target star, the efficiency curves shown in Figure 4 should be used.
		These curves, which give the 14 sec count rate as a percentage of the photon flux incident on the unocculted 2914 cm² of the primary mirror, are based on calibrated rocket data compiled by R.C. Bohlin (private communication) for the star Eta UMa.
	archive.stsci.edu /copernicus/gi_guide/sect3.html (2250 words)

	Arrhenius English
		The selective diffusion is extraordinarily great for the ultra-violet rays, and diminishes continuously with increasing wave-lengths of the light, so that it is insensible for the rays that form the chief part of the radiation from a body of the mean temperature of the earth.
		The researches of Paschen show that these gases are both very effective, so that probably sometimes the one, sometimes the other, may have the greater effect according to the circumstances.
		In Paschen's curve there are traces of a continuous absorption by the carbonic acid in this whole region with weak maxima at lambda = 5.2 micron, lambda = 5.9 micron, lambda = 6.6 micron (possibly due to traces of water-vapour), lambda = 8.4 micron, and lambda = 8.9 micron.
	hps.elte.hu /~zagoni/Arrh1.htm (3436 words)

	Electrostatics and Surface Physics Laboratory
		In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes.
		For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries.
		It should be noted that Paschen curves are experimental and depend on several factors such as gas content, pressure, distance, geometry, wind velocity, electrode composition, etc. Thus true Paschen measurements should only be performed on Mars.
	empl.ksc.nasa.gov /CurrentResearch/Breakdown/Breakdown.htm (732 words)

	Pseudospark Switches
		The Paschen curve is a plot of breakdown voltage for gases as a function of the product of gas pressure and electrode separation.
		Longer gaps reduce the electric field strength and consequently reduce the kinetic energy of the electrons which is why longer gaps require higher voltages to initiate plasmas.
		Now remember that the x-axis of the Paschen curve is not pressure, but the product of pressure and distance.
	members.tm.net /lapointe/Pseudospark_Switches.html (1444 words)

	Conduction and Breakdown in Gases - Part 1 (Site not responding. Last check: 2007-10-20)
		Paschen's Law Paschen's law describes how breakdown voltage varies with gas pressure, p, and gap spacing, d.
		Paschen's law applies only to uniform field electrode gaps where the maximum E field exists within the gap and is given by V/d and is uniform within the interelectrode space.
		Note: In this section on Paschen's curve, Townsend's first ionization coefficient was approximated by the functions given in Chapter 14 of Principles of Plasma Discharges and Materials Processing, by M. Lieberman and A. Lichtenberg, NY: Wiley, 1994.
	www.eecs.wsu.edu /~pedrow/HV_Engineering/lecture/bdgas/part1 (291 words)

	Patent 4535345: Ion projection printer with extended back electrode
		As the distance of separation increases, the electric field increases, causing the Paschen breakdown voltage to be reached and disruptive charge transfer to occur.
		The phenomenon of electrical breakdown of an air gap (disruptive charge transfer) is explained by Paschen's law and may be graphically represented for air by curve A of FIG.
		Looking at curve A from right to left, it can be seen that as the gap between charge bearing surfaces gets smaller the breakdown voltage decreases and arrives at a minimum of about 360 volts at about 7.5 microns.
	www.freepatentsonline.com /4535345.html (2869 words)

	Sam's Laser FAQ - Helium-Neon Lasers
		Curved mirrors result in an easier to align more stable configuration but are more expensive than planar mirrors to manufacture and are not as efficient since less of the lasing medium volume is used (think of the shape of the beam inside the bore).
		It is possible to widen the gain curve somewhat by using a mixture of neon isotopes (Ne and Ne) rather than a single one since the location of their peak gain differ slightly.
		Curved mirrors result in an easier to align more stable configuration but may be more expensive than planar mirrors to manufacture.
	repairfaq.cis.upenn.edu /sam/laserhen.htm (21094 words)

	Investigation of the Paschen Curve of Nitrogen via the Application of Nanosecond Pulsed ElectroMagnetic Radiation - ...
		Abstract: In order to obtain lasing in microwave excited gases, a knowledge of the Paschen curve is required so that estimates can be made of the required intensity of the electromagnetic field for a given pulse duration.
		The Paschen curve of nitrogen from pressures of 0.336 Torr via the application of nanosecond pulsed electromagnetic radiation has been investigated.
		In order to obtain lasing in microwave excited gases, a knowledge of the Paschen curve is required so that estimates can be made of the required intensity of the electromagnetic field for a given pulse duration.
	www.stormingmedia.us /92/9210/A921092.html (358 words)

	Empfasis - Ask The EMPF Helpline!
		The dielectric breakdown of air is defined by Paschen’s Law (V = f{pd}) or the Paschen curve.
		The curve is usually written as a graph of breakdown voltage (V) vs. the product of gas density (sometimes referred as pressure (p)) and gap size (d).
		For the designer, it should be noted that while the curve is defined by the function of the gas density and gap size, many other factors such as radiation, dust, surface irregularities, and humidity have an effect on the breakdown of a gap.
	www.empf.org /empfasis/july04/help704.htm (916 words)

	Alphatron Linac
		The Paschen curve defines the breakdown voltage in gases as a function of pressure and distance and leads to grid/anode structures separated by 3 mm inside the envelope and by 75 mm outside the envelope.
		Thyratron high voltage structures are designed in accordance with the Paschen curve and field emission constraints to give reliable performance at 25 kV and above in line-type modulators.
		Thyratron commutation is initiated by fast rising trigger pulses to the grid(s) which fill the cathode/grid region with plasma.
	www.alphatronlinac.com /index.php?page=thyratron-prin (599 words)

	Annual Report 2004 -- Laser Physics Department (Site not responding. Last check: 2007-10-20)
		Unexpected "wings" appeared on the two sides of the autocorrelation curve (Fig.1) indicating a certain (~20 fsec long) life time lengthening suggesting ultrafast hot electron dynamics reducing the mentioned dependence of the efficiency of the high order multiphonon emission on the absolute phase.
		The breakdown characteristic (Paschen curve) of a hollow-cathode argon discharge has been studied with Monte Carlo simulation and experiments.
		In the field of strongly coupled plasmas we have studied the thermal conductivity of three-dimensional Yukawa plasmas in the liquid phase.
	www.szfki.hu /yearbook/current/lezfiz.html (1457 words)

	Redeye Users' Manual: Filters
		These curves were made with the IRTF's lab IR spectrometer in Honolulu.
		In all cases, a "cold" curve corresponds to the filter at 77 K, while a "warm" curve corresponds to 295 K. For the narrow band filters in particular, this change in temperature shifts central wavelengths a significant fraction of the central band passes.
		Finally, digital versions of these transmission curves, in the form of ASCII text files, are available via anonymous ftp to ftp.cfht.hawaii.edu, in the same manner as this entire manual (see Chapter 1).
	www.cfht.hawaii.edu /Instruments/Detectors/IR/Redeye/Manual/chapter4.html (1401 words)

	english.v (Site not responding. Last check: 2007-10-20)
		Townsend coefficient and a Pascen curve for neon
		The curve of a leav-ing for a Neon, dividing area of an effective multiplication of electrons and area, in which the electrons abandon discharge gap, having insufficient time to multiplicate, is obtained.
		On basis of the obtained curve of leaving the analog of Paschen curve is constructed.
	zhurnal.ape.relarn.ru /articles/2004/085.html (151 words)

	Patent 4034260: Gridded crossed-field tube and ignition method
		4 is a Paschen curve relating the conditions in the interelectrode gaps to the conductive region of the Paschen curve.
		4 and 5) which is the leftward end of the toe of Paschen curve 78 which separates the conductive region 80 from the nonconductive region 82.
		When on-switching is desired, for example at point t.sub.1, switch 42 is closed to impress a pulse between the cathode K and the control electrode C to bring the voltage therebetween into the conductive region of the Paschen curve, for example to point 86 in FIG.
	www.freepatentsonline.com /4034260.html (2929 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		Before reaching the first Paschen minimum A (0.6 mbar) in the absence of magnetic field, we can say that for high pressures and short mean free paths, the combined effects of decreasing the pressure with higher B fields could produce the electric crossing conditions (D, E and F).
		For pressures lower than 10-1 mbar (the Paschen minima are reached for the B field curves) there are electric inversions points at approximately 8 INCRUSTAR Equation.3 10-2 mbar (point G) and 3,5 INCRUSTAR Equation.3 10-2 mbar (point H).
		These phenomena are due to the anomalous diffusion characteristics of the glow discharge with a longitudinal magnetic field centered at the cathode fall [5], observed experimentally at the positive column by Hoh and Lehnert [6], Allen, Paulikas and Pyle [7], and explained theoretically by Kadomtsev and Nedospadov [8] and Johnson, et al, [9, 10].
	www.pucp.edu.pe /~gip/articles/articulo_paschen.doc (887 words)

	Dictionary of Technical Terms for Aerospace Use - P (Site not responding. Last check: 2007-10-20)
		An open curve all points of which are equidistant from a fixed point, called the focus, and a straight line.
		Radiation may become polarized because of the nature of its emitting source, as is the case with many types of radar antennas, or because of some processes to which it is subjected after leaving its source, as that which results from the scattering of solar radiation as it passes through the earth's atmosphere.
		Geometrically, the probability integral equals the area under this density curve between -z and z, where z is an arbitrary positive number.
	sulu.lerc.nasa.gov /dictionary/p.html (11606 words)

	Peoria Astronomical Society - Learning Topics-Astronomical Glossary
		A closed curve enclosing two points (foci) such that the total distance from one focus to any other point on the curve back to the other focus equals a constant.
		The emission spectrum of the chromosphere that is visible for the few seconds during a total solar eclipse when the moon has covered the photosphere but has not covered the chromosphere.
		A model of the universe in which space-time is not curved.
	www.astronomical.org /portal/modules/wfsection/article.php?articleid=131 (4317 words)

	CE Magazine: Mr. Static
		Figure 6, known as Paschen's curve, shows the breakdown voltage for plane electrodes in atmospheric air as a function of the product of the atmospheric pressure and the electrode distance.
		The curve also shows that there is a minimum breakdown voltage of about 330–340 V, corresponding at 1 atm to a distance of 5–6
		For that same reason, the lower value of 300 V of Paschen's curve cannot be applied to insulators.
	www.ce-mag.com /archive/02/01/MrStatic.html (2320 words)

	Method and device for the generation of far ultraviolet or soft x-ray radiation patent (Site not responding. Last check: 2007-10-20)
		In a method for generating extreme ultraviolet radiation or soft x-ray radiation by means of gas discharge, in particular, for EUV lithography, a discharge vessel is provided with two electrodes that are connected to high voltage.
		Between the electrodes, in an area of two electrode recesses that are coaxial to one another, a gas fill with predetermined gas pressure in accordance with a discharge operation realized on the left branch of the Paschen curve is provided.
		The pressure of the gas and the electrode distance are selected such that the system operates on the left branch of the Paschen curve and, as a result of this, no dielectric firing between the electrodes occurs.
	www.freshpatents.com /Method-and-device-for-the-generation-of-far-ultraviolet-or-soft-x-ray-radiation-dt20050224ptan20050040347.php (2776 words)

	Friedrich Paschen
		He established the now widely used Paschen curve in his article "Über die zum Funkenübergang in Luft, Wasserstoff and Kohlensäure bei verschiedenen Drücken erforderliche Potentialdifferenz" (Weid.
		This page was last modified 06:39, 13 Feb 2005.
		The article about Friedrich Paschen contains information related to Friedrich Paschen.
	www.arikah.net /encyclopedia/Friedrich_Paschen (84 words)

	Encyclopedia: Friedrich Paschen (Site not responding. Last check: 2007-10-20)
		Friedrich Paschen(January 22, 1865-February 25, 1947) was a 19th century physicist, known for his work on electrical discharges.
		Paschens Law, named after Friedrich Paschen, was first stated in Wied.
		Click for other authoritative sources for this topic (summarised at Factbites.com).
	www.nationmaster.com /encyclopedia/Friedrich-Paschen (224 words)

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