PH0101 Unit 2 Lfgjfgjecture 6

7/26/2019 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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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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)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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*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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*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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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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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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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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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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!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.

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PH0101 Unit 2 Lfgjfgjecture 6