A Path to Ph.D. in the Field of Applied Superconductivity at Graduate School of Applied Electromagnetism

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Nov 15, 2013 (3 years and 10 months ago)

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AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.1/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
APathtoPh.D.intheFieldof
AppliedSuperconductivity
atGraduateSchoolofAppliedElectromagnetism
AnttiStenvall
antti@stenvall.fi
TampereUniversityofTechnology
Electromagnetics
GroupofAppliedSuperconductivity
FINLAND
http://www.tut./smg
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.2/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Contents
Superconductivity,excursiontoteaching,learningandresearch...
PurposeistomakeyouthinksomethingelsethansolvingMaxwell's
equationsatleastforawhile.
Hopefullyyouwillaskyourselfafterthis:
WhyIdomyresearch?
Whataremygoals?
WhatdoIwanttodoafterPh.D.?
...
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.3/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Resistivity
Material
Current
Voltage
Resistance, resistivity
Weallhavean(erronous?)impressionof
currentandvoltage.Let'sskipthat.
Weapplyavoltagetoabodyfromone
connectionpointtootherandgetacurrent
whichdependsonmaterial,etc.
Wesaythatbodyhasresistanceand
materialhasresistivity.
Nobodyreallyknowshow/whyresistivity
arises.
Atsuperconductingstatewecanhavecurrentwithoutvoltage.
Resistivitygoestozero.Thus,resistancedoesnotdependon
connectionpoints.
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.4/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Superconductivitycont.
Superconductivityischaracterisedbytwoproperties
1.Resistivityis0
2.Magneticuxdensitydoesnotpenetrateintothesuperconductor
Isthisagooddenitionforasuperconductor?
Superconducting
coil
Current source
No work required to keep the current running
Current
SC
Howtondoutifagivenpieceissuperconductor?
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.5/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Howtoreally...
...ndoutifagivenpieceofmaterialisasuperconductor(i.e.itisina
superconductingstate)?
Itseemstomethatresistivitycanbemeasuredrelativelynicely→
atvoltagecurrentmeasurementofasuperconductornoworkis
neededtokeepthecurrentrunning
BUThowtomeasurea-man-invented-toolcalledmagneticux
densityINSIDEthesuperconductor?(bythewaytheeffectof
magneticuxrepulsioniscalledtheMeissnereffect)
Doesabrickhaveinside?TrytoOBSERVEit.
.......
Only outsides
visible
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.6/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
ExampleofBADlearning(andteaching)
Q:WhatisMeissnereffectinsuperconductors?
A:Meissnereffectmeansthatmagneticeld(uxdensity,whatever)
doesnotpenetrateintothesuperconductor.
Whyshouldweavoidthisinlearning,teachingandESPECIALLYin
researchinganddoingaPh.D.?
Ifyouteachthistoastudentwhatdoesheknowfromthebehaviourof
thenature?Ifyoudoresearchinthiswaywhatdoyouknowaboutthe
nature?
Bytheway,thereisnouseknowingwhat,say,DIAMAGNETISM
meansifonedoesnotknowanydiamagneticmaterials(samewith
superconductivity-ofcourse).
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.7/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Abetterway-SUGGESTION(notanswer)
Ifyoutakeasuperconductorandcoolitdownandputitona
permanentmagnet(ortheotherwayround)itlevitates.
Thereisatheoryonthatbutnobodyreallyknowswhyithappens.
Really,nobodyknows.Otherwisepeoplewouldalsoknowbefore
measurementswhichmaterialsaresuperconducting.Somereal
physicistwilltellyouaboutthetheorysomeotherlecture.
Bytheway,thiseffectiscalledtheMeissnereffect.
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
p.8/9
HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Suggestionforbasicelectromagnetism
Appliesalsotobasiccircuitanalysiscourses
Spendacoupleofrstweeksinthelab
Givecertaintoolstostudentsandonlybitinstructions
Askthemtoreturnreportswheretheywritedownwhatthey
observedandwhattheydidnot
Afterthelab,teachthetheorywithdemonstratingagainthe
experimentsintheclass
ForFinnishpeople:seehttp://netti.nic.fi/~054028/tonda
methodIappreciate
AnttiStenvallantti@stenvall.APathtoPh.D.intheFieldofAppliedSuperconductivityatGraduateSchoolofAppliedElectromagnetism
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HotelVaakunaAugust28-292008,AnnualSeminarofGraduateSchoolofElectromagnetics.
Doingresearchforthedegreeofdoctor
IsbalancingbetweenPERFORMANCEanddesiretowidenown
scaleofknowledge
Remembertotakeadvantageofthegraduateschoolposition
Takeavacationfromproductivelabour(=makingpublications
inFinnishGoverment,gettingcrossestothetablesofthe
cofferguards)
Dowhatinterestsyouthemostinscience
Butremembertograduate
ForFinnishpeople:seehttp://netti.nic.fi/~054028/tonda
methodIappreciate