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Topic: Adiabatic demagnetization

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	Adiabatic Process Encyclopedia Article @ Peculiarities.org (Site not responding. Last check: 2007-10-08)
		Another example is the adiabatic flame temperature, which is the temperature that would be achieved by a flame in the absence of heat loss to the surroundings.
		Adiabatic heating and cooling are processes that commonly occur due to a change in the pressure of a gas.
		If adiabats and isotherms are graphed severally at regular changes of entropy and temperature, respectively (like altitude on a contour map), then as the eye moves towards the axes (towards the south-west), it sees the density of isotherms stay constant, but it sees the density of adiabats grow.
	www.peculiarities.org /encyclopedia/Adiabatic_process (1252 words)

	Magnetic refrigeration - Wikipedia, the free encyclopedia
		This is also known as adiabatic demagnetization by low temperature physicists, due to the application of the process specifically to effect a temperature drop.
		The randomization of the domains occurs in a similar fashion to the randomization at the curie temperature, except that magnetic dipoles overcome a decreasing external magnetic field while energy remains constant, instead of magnetic domains being disrupted from internal ferromagnetism as energy is added.
		When the magnetic field is subsequently switched off, the heat capacity of the refrigerant rises again because the degrees of freedom associated with orientation of the dipoles are once again liberated, pulling their share of equipartitioned energy from the motion of the molecules, thereby lowering the overall temperature of a system with decreased energy.
	en.wikipedia.org /wiki/Adiabatic_demagnetization (2603 words)

	Electromagnetic heat engines and method for cooling a system having predictable bursts of heat dissipation - Patent ... (Site not responding. Last check: 2007-10-08)
		Adiabatic switching and reversible computation require lowering of the operating speed, and are inapplicable to existing systems because different logic design principles are prescribed.
		Thereafter, the dropping current causes demagnetization, and heat must be transferred into the medium to maintain its temperature at T.sub.h, till the current drops to i given by ##EQU35## where c is the applicable specific heat of the medium.
		The demagnetization phase is arranged to occur throughout the transitions, so that the local thermodynamic state follows the typical path abcda in the figure.
	freepatentsonline.com /5714829.html (11730 words)

	Definitions (Site not responding. Last check: 2007-10-08)
		A phase transition of a superconductor in which the superconductor is held at a constant temperature because it is thermally connected to a heat reservoir at that temperature.
		Such a process is known as an "Adiabatic Demagnetization." Both of these described processes are known as the "magneto-caloric effect" and are the result of latent heat exhibited at the phase transition which is exchanged with the internal energy of the superconductor (the phase transition being adiabatic).
		A non-zero demagnetization factor (or coefficient) is usually present unless the superconductor is a thin cylinder oriented parallel to the magnetic field.
	www.keefengine.com /Terminology.htm (2285 words)

	Magneto Thermodynamics, Part 3
		Adiabatic demagnetization during step two, causing un-paired electron spin population (working fluid) temperature to momentarily fall below the Curie transition temperature (3.1.3), thereby allowing ferromagnetic spin coupling forces to momentarily dominate.
		During this step, as un-paired electron spins align with the applied magnetic field, the entropy of the population declines, and heat flows out of the un-paired electron spin population, and into the bulk material population (3.1.2).
		Step 2 (adiabatic demagnetization) causes a rapid decline in the temperature of the un-paired electron spin population (3.1.5).
	www.geocities.com /electrogravitics/mt3.html (1982 words)

	PI3 (Site not responding. Last check: 2007-10-08)
		The technique called cooling by adiabatic demagnetization is a very well known method to produce very low temperatures.
		The basic idea is, that if a paramagnetic material placed in an external magnetic field is decoupled from its environment, a subsequent reduction of the magnetic field leads to a reduction of the temperature of the paramagnet.
		Nowadays, with the advent of ingeniously designed materials, adiabatic demagnetization is even considered for applications in household refrigerators where it could avoid the need for poisonous refrigerants.
	www.pi3.physik.uni-erlangen.de /cool_ferric_wheels.html (498 words)

	XQC
		The XQC detector is composed of a 36 pixel microcalorimeter array attached to an adiabatic demagnetization refrigerator operating at 60 mK.
		This is achieved using a liquid helium dewar and an adiabatic demagnetization refrigerator (ADR).
		The adiabatic demagnetization refrigerator is the ultra low temperature refrigerator for the microcalorimeter detectors.
	wisp11.physics.wisc.edu /xray/experiments/xr_xqc.htm (684 words)

	Quantum Transport Research Lab
		The dilution unit is used to cool a large high purity copper demagnetization stage, housed inside a 9 Tesla superconducting magnet.
		Below the demagnetization magnet we have another powerful superconducting magnet to provide the conditions required for studying electron transport in 2 dimensions.
		The project is currently in the last phases of finishing and testing the demagnetization stage.
	www.ruf.rice.edu /~dulab/ResearchUltraCold.html (459 words)

	Physics News Update
		The spins constitute a system all by themselves and can be "cooled" adiabatically (that is, without heat flowing in or out) by decreasing the strength of an applied magnetic field.
		This "adiabatic demagnetization" was routinely used to achieve the low temperatures (milli-kelvin) needed for studying helium-3.
		This adiabatic magnetization was achieved with "ferric wheels," ring-shaped molecules featuring six iron atoms plus a few ligand hangers-on (see figure).
	www.aip.org /pnu/2002/split/615-2.html (254 words)

	Study demonstrates magnetic cooling in gas
		Magnetic refrigeration, also known as adiabatic demagnetization cooling, works by exposing suitable materials to a changing magnetic field.
		In their study the authors showed that in a gas made of chromium-52 atoms, a coupling exists that is strong enough to allow efficient magnetic refrigeration.
		The researchers propose a broader class of gases might be amenable to adiabatic demagnetization cooling, and expect that the method could become a useful way to reach temperatures near absolute zero in gases, providing a rich assortment of phenomena for physicists to explore.
	www.softcom.net /webnews/wed/bu/Ugermany-cooling.RvaH_GN1.html (207 words)

	notes to negative kelvin
		The particles tend to accumulate at the lower energy state, the orientation is not random anymore, and hence entropy is lowered.
		Cooling by adiabatic demagnetizing goes like this: a sample at state (1) is magnetized in thermal contact with a heat bath.
		But the demagnetization step occurs at constant entropy: if the demagnetization is done very slowly, so that no turbulence would shuffle the molecules, no entropy is generated.
	www.maxwellian.demon.co.uk /art/esa/negkelvin/adiademg.html (792 words)

	Cryogen-free Adiabatic Demagnetization Refrigerator by Janis Research Company
		Janis Research has announced a cryogen-free, two-stage adiabatic demagnetization refrigerator (ADR) and superconducting magnet system.
		Standard thermometry is supplied at the two stages of the ADR, at the two stages of the refrigerator, and at the magnet.
		Power supplies are available for charging and discharging the magnet during the magnetization and demagnetization cycles.
	www.janis.com /news0701.html (134 words)

	Overturning of Parity Law in Nuclear Physics
		Magnet on either side of the specimen was used to cool it to approximately 0.003 K by adiabatic demagnetization.
		Cooling to the low temperature necessary for nuclear alignment was accomplished by the process of adiabatic demagnetization using a magnetic field of about 2.3 tesla (23,000 gauss).
		The specimen was then thermally isolated and upon demagnetization the temperature fell to about 0.003 K. NBS physicist adds liquid nitrogen refrigerant to outer flask of cryostat containing sample of cobalt-60.
	physics.nist.gov /GenInt/Parity/expt.html (1760 words)

	Adiabatic Demagnetization Refrigerator Systems - Janis Research (via CobWeb/3.1 planetlab1.cs.wisc.edu) (Site not responding. Last check: 2007-10-08)
		The adiabatic demagnetization refrigerator (ADR) systems from Janis Research offer a simple method of achieving temperatures of 50 mK.
		These systems include a conductively cooled superconducting magnet, which is used to magnetize the two pills, and a mechanical heat switch that links and isolates the two stages from the 4 K surface.
		After magnetizing the pills at 4 K, the pills are isolated from the 4 K surface and demagnetized to achieve the lowest temperature.
	www.janis.com.cob-web.org:8888 /p-adr.html (311 words)

	XACT Facility (Site not responding. Last check: 2007-10-08)
		An Adiabatic Demagnetization Refrigerator (ADR) has been set up at the XACT facility (Barbera et al.
		The Adiabatic Demagnetization Refrigerator of the XACT facility.
		Control panel for pumping liquid He and N in order to lower the temperature of the paramagnetic salt down to about 1.8 K before the isothermal magnetization/adiabatic demagnetization cycle is conducted.
	www.astropa.unipa.it /XACT/adr.html (151 words)

	Re: What is adiabatic nuclear demagnetization?
		Adiabatic demagnetization is an ingenious method to achieve very low temperatures.
		It depends on a simple thermodynamical fact: If one blocks all heat flow to and from a system, the overall entropy in the system cannot change (change in entropy is heat flow devided by temperature).
		So if it is possible to find a material in which electron spins do not contribute significantly to magnetism, nuclear adiabatic demagnetization can be used to reach temperatures in the microkelvin range.
	www.madsci.org /posts/archives/oct99/939387631.Ph.r.html (970 words)

	XRS
		The X-ray microcalorimeters, the Adiabatic Demagnetization Refrigerator (ADR) and the liquid helium tank have been supplied by GSFC.
		The XRS detector assembly (named Front End Assembly - FEA) is placed inside the helium tank and is thermally connected to the Adiabatic Demagnetization Refrigerator (ADR), which cools the FEA down to 65 mK.
		The spins of the salt molecules are thereby allowed to flip in random directions to reach a high entropy state (adiabatically demagnetized).
	heasarc.gsfc.nasa.gov /docs/suzaku/about/xrs_inst.html (2150 words)

	Constellation-X :: Science :: Technology :: X-ray Microcalorimeter System
		The first space flight Adiabatic Demagnetization Refrigerator (ADR) was developed and qualified for the XRS instrument.
		The XMS detector assembly will be cooled to 50 mK using a "continuous" adiabatic demagnetization refrigerator.
		Conventional ADRs use a discrete process in which the refrigerant is first magnetized (warming it up and allowing heat to be rejected to a heat sink), and then demagnetized to cool to low temperature.
	constellation.gsfc.nasa.gov /mission/technology/xms.html (1644 words)

	Adiabatic Demagnetization Refrigerator t-60s (via CobWeb/3.1 planetlab1.cs.wisc.edu) (Site not responding. Last check: 2007-10-08)
		CSP Cryogenic Spectrometers GmbH is offering a fully automated cryostat for the temperature range between 60 mK and 4.2 K based on an adiabatic demagnetization refrigerator (ADR).
		To stabilize the salt pill above base temperature, the ramp is stopped at the specific temperature and the magnetic field is reduced slowly to compensate for the residual heat leak.
		During adiabatic demagnetization the salt pill is cooled down to 100 mK and is stabilized at its operating temperature for more than 8 hours.
	www.konzept139.de.cob-web.org:8888 /csp/t-60s.htm (251 words)

	A.M. Dyugaev , I.D. Vagner, P. Wyder: Nuclear ferromagnetism induced Fulde-Ferell-Larkin-Ovchinnikov state (Site not responding. Last check: 2007-10-08)
		We outline that the optimal experimental conditions for observation of FFLO could be achieved by creation, via adiabatic nuclear demagnetization, of the negative nuclear spin temperatures.
		is the nuclear magnetization and n is the demagnetizing factor, depending on the sample form.
		Two experimental metodiques of nuclear spin cooling should be considered: the adiabatic demagnetization and the dynamic polarisation.
	www.magniel.com /hmtj/papers/dvw01/dvw.html (2086 words)

	Wed. 15 Jan. 1997: The Boltzmann Distribution (Site not responding. Last check: 2007-10-08)
		That is, the microscopic state of the spin system does not change during this process, nor, therefore, does the entropy.
		one can use adiabatic nuclear demagnetization, for which typical magnetic moments are several thousand times weaker.
		The coldest temperatures ever achieved in laboratories on Earth use huge refrigerators several stories high (with elaborate vibration-free mountings) with a final stage based on adiabatic nuclear demagnetization.
	musr.physics.ubc.ca /~jess/p455/Lectures/L05_97.html (840 words)

	[No title]
		The upper curve shows the variation of the entropy of a paramagnetic system in the absence of an applied field.
		The lower curve shows the variation in entropy when a field is applied and has made the electron magnets more orderly.
		The isothermal magnetization step is from A to B; the adiabatic demagnetization step (at constant entropy) is from B to C. ¤.¥ÂA¦ § ÐÏà¡±á>þÿ þÿ_àòùOh«‘+'³Ù0°Ü$ Hl ´ØSummaryInformationÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ(ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿàÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÀýÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÀþÿÿÿÀäôÀþÿÿÿ ÿþþÿÿÿÀûÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÀüÿÿÿþÿÿÿüÿÿÿ ü D hP ÿÿÿÿWorC:\WINWORD\TEMPLATE\NORMAL.DOTThe technique of adiabatic demagnetization is used to attain very low temperatures.
	www.cobalt.chem.ucalgary.ca /ziegler/Atkins/chap4/rtf/f4_11.doc (188 words)

	[No title] (Site not responding. Last check: 2007-10-08)
		ENTROPY (c) Paul Kinsler 1996 February 10 Note: this kicks off with a brief discussion of adiabatic demagnetization, which is where the conversation started.
		Well, the material consists of small magnetic dipoles surrounded by an adiabatic wall.
		The field contains energy, and is not affected by the adiabatic wall.
	www.moo.uklinux.net /kinsler/ircph/files/entropy.html (569 words)

	Constellation-X :: Science :: Technology :: Cooling System
		An Adiabatic Demagnitization Refridgerator (ADR) stores heat in the disorder of magnetic moments of the moleculres in a paramagnetic substance, a "salt pill".
		Also, because a single-shot ADR must store heat for extended periods of time, the relatively low entropy density of magnetic refrigerants translates to large system size and mass.
		The CADR under development uses multiple stages arranged sequentially, with each salt pill connected to the next stage (or to the heat sink) by a heat switch.
	constellation.gsfc.nasa.gov /mission/technology/cooling.html (447 words)

	Cryogenics - MSN Encarta
		Introduction; Development; Adiabatic Demagnetization; Change in Properties; Applications
		Cryogenics, study and use of materials at very low temperatures.
		This procedure requires that a magnetic field (see Magnetism) be established around a paramagnetic substance, that is, a substance made of paramagnetic ions, while the substance is cooled in liquid helium.
	encarta.msn.com /encyclopedia_761563758/Cryogenics.html (1137 words)

	Volume heating and cooling: Adiabatic demagnetization and (Site not responding. Last check: 2007-10-08)
		Adiabatic demagnetization with appropriate magnetic fluids can, in principle, offer the same advantage with respect to cooling.
		Upon demagnetization it would cool due to entropic effects.
		This is essentially the way liquid helium is brought to temperatures near absolute zero.
	www.cryonet.org /cgi-bin/dsp.cgi?msg=18924 (164 words)

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