Emittance measurement of the Naval Postgraduate School Linear Accelerator using optical transition radiation techniques

138 Pages·1.8 MB·en_US

by  Hellstern, Mark Joseph.;Maruyama, Xavier K.

NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
EMITTANCE MEASUREMENT OF THE NAVAL
POSTGRADUATE SCHOOL LINEAR ACCELERATOR USING
OPTICALTRANSITION RADIATION TECHNIQUES
by
Mark Joseph Hellstern
September 1991
Thesis Advisor: Xavier K. Maruyama
Approved for public release; distribution is unlimited
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4 PERFORMINGORGANIZATIONREPORTNUMBER(S) 5 MONITORINGORGANIZATIONREPORTNUMBER(S)
6a NAMEOFPERFORMINGORGANIZATION 6b OFFICESYMBOL 7a NAMEOFMONITORINGORGANIZATION
NavalPostgraduateSchool (Ifapplicable) NavalPostgraduateSchool
33
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Monterey,CA 93943-5000 Monterey,CA 93943 5000
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11 TITLE(IncludeSecurityClassification)
EMITTANCE MEASUREMENTOFTHENAVALPOSTGRADUATESCHOOLLINEARACCELERATORUSINGOPTICALTRANSITION
RADIATIONTECHNIQUES
12 PERSONALAUTHOR(S) Hellstern,MarkJ.
13a TYPEOFREPORT 13b TIMECOVERED 14 DATEOF REPORT(year,month,day) 15 PAGE COUNT
Master'sThesis From To September 1991 128
16 SUPPLEMENTARYNOTATION
Theviewsexpressed inthisthesisarethoseoftheauthoranddonotreflecttheofficialpolicyorpositionoftheDepartmentofDefenseortheU.S.
Government.
17 COSATICODES 18 SUBJECTTERMS(continueonreverseifnecessaryandidentifybyblock number)
FIELD GROUP SUBGROUP opticaltransitionradiation,chargedparticlebeams,freeelectronlasers,beamdiagnostics
19 ABSTRACT(continueonreverseifnecessaryandidentifybyblocknumber)
UsingOpticalTransitionRadiation(OTR)beamdiagnosticsandDr. Rule'sclearfoilinterferometeranalyticcode,thenormalizedemittanceof
theNavalPostgraduateSchool(NPS)linearaccelerator(linac)hasbeemmeasured: thenormalizedhorizontalemittanceof97pi+/-10pimm-
mradandthenormalizedverticalemittanceof54pi+/-8pimm-mrad. Theexperimentwasperformedindependentlytwiceusinga Kapton
foil/siliconmirrorandanitrocellulosefoil/aluminum mirrorWartski interferometer. The Kaptonfoilprovidedaninitialmeasurementofthe
emittance,andprovidedthelessonslearnedforthenitrocellulosemeasurement. TheemittanceoftheNPSlinacindicatethatthevaluemaybe
toohighformostfreeelectronlaserapplications,butisveryusefulforradiationeffectstudiesinhightemperaturesuperconductors,hardening,
beamdiagnostics,andfortheproductionofx-raysthroughnovelmechanismssuchastransitionradiationandparametricx-radiationgeneration.
ThebeamdivergencewasdeterminedbycomparingthetheoreticallycalculatedOTRpatternswiththeexperimentaldataOTRpatterns. The
clearfoilamplitudealgorithmsinthecodehavebeenvalidated inthenitrocelluloseanalysis. Inaddition,thinclearfoils,whichapproximatethe
radiationcoherencelengthinthefoilmedium,providehighdegreesofsensitivitytothefoil'sindexofrefraction,indicatingthatOTRmatbeused
todetermineindicesofrefractioninadditiontomeasuringbeamdivergence. ThediagnosticcapabilitiesofOTRareprovenasapplicableto
electronaccelerators(includingfreeelectronlasers).
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Approved for public release; distribution is unlimited.
Emittance Measurementofthe Naval Postgraduate School
LinearAccelerator Using Optical Transition Radiation Techniques
by
Mark J. Hellstern
Lieutenant, United States Navy
B. S., United States Naval Academy
Submitted in partial fulfillment
ofthe requirements for the degree of
MASTER OF SCIENCE IN PHYSICS
from the
NAVAL POSTGRADUATE SCHOOL
September 1991 *
11
ABSTRACT
Using Optical Transition Radiation (OTR) beam diagnostics and Dr.
Rule's clear foil interferometer analytic code, the normalized emittance of the
Naval Postgraduate School (NPS) Linear Accelerator (linac) has been
measured: the normalized horizontal emittance of 91n +/- IOtc mm-mrad and
the normalized vertical emittance of 54tc +/- 8tc mm-mrad. The experiment
was performed independently twice using a Kapton foil/silicon mirror and a
nitrocellulose foil/aluminum mirror Wartski interferometer. The Kapton foil
provided an initial measurement of the emittance, and provided lessons learned
for the nitrocellulose foil measurement. The emittance measurement of the
NPS linac indicate that the value maybe too high for most free electron laser
applications, but is very useful for radiation effect studies in high temperature
superconductors, hardening, beam diagnostics, and for the production of x-rays
through novel mechanisms such as transition radiation and parametric x-
radiation generation.
The beam divergence was determined by comparing theoretically
calculated OTR patterns with the experimental data OTR patterns. The clear
foil amplitude algorithms in the code have been validated in the nitrocellulose
foil analysis. In addition, thin clear foils, which approximate the radiation
coherence length in the foil medium, provide high degrees of sensitivity to the
foil's index of refraction, indicating that OTR may be used to determine indices
of refraction in addtion to measuring divergence. The diagnostic capabilities of
OTR
are proven as applicable to electron accelerators (including free electron
lasers).
TABLE OF CONTENTS
INTRODUCTION
I. 1
A. HISTORICAL BACKGROUND
1
TRANSITION RADIATION AS A DIAGNOSTIC TOOL
B. 2
MEASUREMENT OF THE NPGS LINAC EMITTANCE
C. 3
THEORETICAL BACKGROUND
II. 6
A. THEORETICAL DEVELOPMENT: SINGLE FOIL 6
OBSERVATION OF OPTICAL TRANSITION RADIATION
B. 10
WARTSKI'S TWO-FOIL INTERFEROMETER
C. 12
D. CLEAR FOIL EFFECTS AND RULES COMPUTER CODE 18
EXPERIMENTAL PROCEDURE
III. 24
A. EXPERIMENTAL SETUP 26
ALIGNMENT OF THE SITCAM
B. 31
C. ANGULAR AND DISTANCE CALIBRATION 34
THE EMITTANCE MEASUREMENT: SEPTEMBER
D. 1990 35
E. COHERENCE, EMITTANCE MEASUREMENTS: NOV. 1990 38
IV. EMITTANCE MEASUREMENT AND DATA ANALYSIS 43
INTRODUCTORY REMARKS
A. 43
B. EMITTANCE MEASUREMENT: KAPTONFOBL 43
C. CLEAR FOIL AMPLITUDE AND COHERENCE EFFECTS 58
THE EMITTANCE MEASUREMENT: NOVEMBER
D. 1990 85
COMPARISON TO OTHER LINACS
E. 101
CONCLUSIONS AND RECOMMENDATIONS
V. 105
A. SUMMARY OF CONCLUSIONS 105
RECOMMENDATIONS
B. 107
IV