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8/7/2019 SAM Physics Assignment - Cryogenics
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Physics Info Search
Prepared by Tan Chang Wei, S5
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What is Low
Temperature Physics??Cryogenics
Greek Kryos means freezing.
- Genes means being generated.Production of low temperature.
Study of phenomena under that temperature.
Started since 19th century by Michael Faraday.
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Production of Low
TemperatureHeat Conduction- Heat from higher temperature body flows to a lower
temperature body.
- Immersed the samples in cryogenics liquid or place incryogenic atmosphere.
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Production of Low
TemperatureEvaporate Cooling- Similar to the mechanism in which our body loses heat.
- Liquid is evaporated and heat from the liquid is used to
convert the particle to gaseous state.- As the process is continued, heat is slowly removed,
temperature drops.
Water
Evaporates
Temp
erat
e
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Production of Low
TemperatureJoule Thompson Effect- Cooling by rapid expansion
- Can also be done by reducing pressure
Temperatur
e
Gas
Airmolecule
s
Valve
P T
Pressure Law
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Production of Low
TemperatureAdiabatic demagnetization- Uses paramagnetic salt-large collection of particle that acts
like tiny magnets
- Used in Adiabatic Demagnetization Refrigerator (ADR)
N S
Temperatur
e
Salts
Liquid givesenergy tothe salts.
Spread out in a liquid, magnetic poles cause the salts to bemagnetic and line up in a same direction.Magnet is removedSalts return to originalpositionLiquid gives energy to the saltTemperature drops
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Application of
CryogenicsDeep Cryogenics Tempering- Improves performances, durability and strength of high alloy
and more.
Superconductivity- Has electrical resistance that is exactly zero, occurs in
certain materials.
- Current still can flow through even there is no Power Supply.
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Application of
CryogenicsRocket Propellants- Fuels and oxidants carried by rockets for propulsion
- Used by NASA
Medical Application- Apply Deep Cryogenics Tempering
- Increase wear resistance of expensive surgical tools
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Application of
CryogenicsAdiabatic Demagnetization Refrigerator (ADR)- Work using properties of heat and the magnetic properties
of certain materials.
- Uses salt pills that is thermally connected to the object to becooled.
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Application of
CryogenicsIndustrial Application- Apply Deep Cryogenics Tempering.
- Increase the wear resistance and strength of the metal.
- Examples: Razors, Clippers, Knives.
Automotive Applications
- Apply Deep Cryogenics Tempering .
- Increase the wear resistance of car engine parts.
- Examples: Piston, The Crank, Push Rods
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Problems of CryogenicsLow spread of low temperature application.
Inconvenient cryoliquids.
SOLUTIONS
Cryogen free alternative to low temperatureapplicationsPulse TubeOn-chip Refrigerator
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