PH0101 Unit 2 Lfgjfgjecture 6
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Transcript of PH0101 Unit 2 Lfgjfgjecture 6
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PH0101 Unit 2 Lecture 6 1
PH0101 Unit 2 Lecture 6
KlystOcil
Refle
Traveling Wave Tue
Biological effect of microaves
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PH0101 Unit 2 Lecture 6 2
Klystron Oscillator
A klystron is a vacuum tube that can beused either as a generator or as anamli!ier o! o"er# at micro"ave
!re$uencies%
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PH0101 Unit 2 Lecture 6 !
&"o cavity Klystron Amli!ier
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PH0101 Unit 2 Lecture 6 "
Alications
As o"er outut tubes
1# in UH$ T% transmitters
2# in tro&os&'ere scatter transmitters!# satellite communication groun( station
"# ra(ar transmitters
As o"er oscillator)* + *0 ,H-./ if use(as a lystron oscillator
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PH0101 Unit 2 Lecture 6 *
'e!le( Klystrons
T'e refle lystron 'as een t'e mostuse( source of microave &oer in
laoratory a&&lications#
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PH0101 Unit 2 Lecture 6 6
)onstruction
3 refle lystron consists of an electron gun/ a cavity it' a&air of gri(s an( a re&eller &late as s'on in t'e aove(iagram#
4n t'is lystron/ a single &air of gri(s (oes t'e functions ofot' t'e unc'er an( t'e catc'er gri(s#
T'e main (ifference eteen to cavity refle lystronam&lifier an( refle lystron is t'at t'e out&ut cavity is
omitte( in refle lystron an( t'e re&eller or reflectorelectro(e/ &lace( a very s'ort (istance from t'e singlecavity/ re&laces t'e collector electro(e#
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PH0101 Unit 2 Lecture 6 5
*orking
T'e cat'o(e emits electrons 'ic' are accelerate(forar( y an accelerating gri( it' a &ositive voltage on itan( focuse( into a narro eam#
T'e electrons &ass t'roug' t'e cavity an( un(ergo
velocity mo(ulation/ 'ic' &ro(uces electron unc'ingan( t'e eam is re&elle( ac y a re&eller &late e&t at anegative &otential it' res&ect to t'e cat'o(e#
On return/ t'e electron eam once again enters t'e samegri(s 'ic' act as a unc'er/ t'ery t'e same &air of gri(s
acts simultaneously as a unc'er for t'e forar( movingelectron an( as a catc'er for t'e returning eam#
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PH0101 Unit 2 Lecture 6
'e!le( Klystron oscillator
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PH0101 Unit 2 Lecture 6 7
*orking
T'e fee(ac necessary for electrical oscillations is(evelo&e( y reflecting t'e electron eam/ t'e velocitymo(ulate( electron eam (oes not actually reac' t'ere&eller &late/ ut is re&elle( ac y t'e negative voltage#
T'e &oint at 'ic' t'e electron eam is turne( ac cane varie( y a(8usting t'e re&eller voltage# T'us t'e re&eller voltage is so a(8uste( t'at com&lete
unc'ing of t'e electrons taes &lace at t'e catc'er gri(s/t'e (istance eteen t'e re&eller an( t'e cavity is c'osen
suc' t'at t'e re&eller electron unc'es ill reac' t'ecavity at &ro&er time to e in sync'roni-ation#
9ue to t'is/ t'ey (eliver energy to t'e cavity/ t'e result ist'e oscillation at t'e cavity &ro(ucing R$ fre:uency#
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PH0101 Unit 2 Lecture 6 10
Per!ormance )haracteristics1# $re:uency; " + 200 ,H-
2# Poer; 1 mW + 2#* W
!# T'eoretical efficiency ; 22#5 3R )>&ecific 3sor&tion Rate. or P9 )Poer 9ensity.# >3R is t'e energy 'ic' is asore( in a unit of mass or
volume of t'e o(y &er unit time# T'e stan(ar(s t'at limit microave e&osure ere set at
0#" WFg >3R for occu&ational an( 0#0WFKg for &ulice&osure#
T'e averaging time for (etermination of >3R as 6minutes# Poer (ensity is t'e energy asore( &er unitarea in unit time# T'e 'ig' &oer microaves (efinitelycause some a(verse effects in t'e 'uman system
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PH0101 Unit 2 Lecture 6 2
3!!ects o! 4icro"ave energyPo"er
level,m* 5cm2-
Longterm e!!ecton human body
'emarks
0#01 Dot'ing
0#1 Dot'ing
1 Dot'ing* Dot'ing 3cce&te( stan(ar( for microave
oven leaage
10 Dot'ing 3cce&te( stan(ar( for maimumcontinuous e&osure to ra(iate(
emissions )cell &'ones/ etc#.!0 Gou can feel 'eat
100 ?ataracts can e&ro(uce(
>ummer sunlig't is at t'is level
1000 Pain is in(uce(
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PH0101 Unit 2 Lecture 6 27
What do Microwave Ovens, Cell Phones and
Cordless Phones have in common?They all emit... Dangerous MicrowaveRadiation!The GOOD NEWSis... with Microwave radiation
you can... Boil water Cook meat Fry eggs
7o you kno" 8OU' +rain can be .'/37999
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PH0101 Unit 2 Lecture 6 !0
T'e +A7 3*:is###
it' @icroave ra(iation you can###
$ry Gour Brain
Gour 'ea( an( rain 'eat u& significantly 'en you tal
on your cell &'one or cor(less &'one#
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PH0101 Unit 2 Lecture 6 !1
Want proof?
After 15 minutes of using a cell phone, the orange, red and pink show
significant, dangerous HEAT.Most heat is generated in your ear canal,
which is directly connected to YOUR RA!"
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PH0101 Unit 2 Lecture 6 !2
!ter "# minutes o! using a cell $hone WITH the BIOPRO
Harmonization Chip applied to it, the green and blue colorsshow cool tissue.
%our head&s tem$erature remains normal, $roviding you with the$rotection you deserve.
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PH0101 Unit 2 Lecture 6 !!
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PH0101 Unit 2 Lecture 6 !"
#roof enough?
$ome scientists estimate that you are now e%posed daily to
1&& million times the electromagnetic fre'uency (Micro
wa)e* radiation of your grandparents+$o+
AVOID FREQUET U!E OF
"E## $HOE!%%%
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PH0101 Unit 2 Lecture 6 !*
Have a nice day.