On the Viability and Requirements of a Barge Based ELF System
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On the Viability and Requirements of a Barge Based ELF System Presentation to Dr. Bobby Junker ONR Code 31 Dennis Papadopoulos University of Maryland December 21,2010
Transcript of On the Viability and Requirements of a Barge Based ELF System
OntheViabilityandRequirementsofaBargeBasedELFSystem
PresentationtoDr.BobbyJunkerONRCode31
DennisPapadopoulosUniversityofMaryland
December21,2010
Outline
• ThePhysicsandExperimentalPoPforUsingHFheaterstoDriveACCurrentsattheIonosphericE‐region(topofEarth‐
IonosphereWaveguide)withouttheneedofejets• Scalingoftheresultswithgeomagneticlocationofheater.
Gainofmorethan40dBnearthedipequator• PossibilityofbargeorshipboardbasedmobileHFheaters
• Importanceofnewresultsto– TacticalandStrategicsubELFcommunications
Q.CanweusegroundHFtogenerateELFatalltimesandprovidestrategicandtacticalcommunicationstosubmarines?
CurrentStatus:Needthepresenceofanelectrojet–PolarElectrojet(PEJ)Ant.
Earth‐IonosphereWaveguide
F‐region
EorHall‐region
density
heightB
H E
I Σ
2.3kHzMidway4.5Mm
1Hz EjetcurrentΙ∼ΣΕ ModulateHFatELFfrequenciestogetMtop~(ΔΣ)ΕLhatthemod.freq.Problem:PolarEjetcurrenthighlyvariable,farfromrelevantregions
Mtop
Q:CanweusegroundHFtogenerateELFatalltimesandprovidestrategicandtacticalcommunicationstosubmarines?
MURI/BRIOCHEChallenge:GenerateELFusingHFwithoutneedinganelectrojet
IonosphericCurrentDrive(ICD)Concept
Step1: MSWave
Step2:
EfieldofMSwavedrivesHallcurrentinE‐regionresultinginsecondaryantennaresemblingPEJ
InjectsSAWupwardsandELFintheEarth‐IonosphereWaveguide
EjetQuiet
ICD
ICD
ICD
ICD
ICD
ICD
ICD
ICD
PEJ
PEJM≈4x109A‐m2
ResultsofDARPA/BRIOCHECampaignChang‐Papadopoulos
ICDExperimentalProof‐of‐Principle
BRIOCHEQPR4NOV20106
350km
11Hz29Hz
47Hz
Gakona
Poker
FarSiteMeasurements
ResultsfromDARPA/BRIOCHE
Chang‐Papadopoulos‐Lebinsky
350km
320km
MS SAWt=4.6sec
GroundBField
ModelValidation MURI/BRIOCHECollaboration
ModelValidation‐FieldConfinementDemeter‐Measurements BRIOCHE
Chang‐Milikh‐Papadopoulos
E‐regioncurrentJθ
BrfieldonthegroundNearfield
Sowhatcreatesthefieldontheground?
Bgr ∝ Jθ∝ΣΕ ∝Σ(λ)PHF
Er
Consequences:1.ICDcanprovideELFatalltimesandatalllatitudes2.Itcanprovideaship‐towedmobileELFsystem
ICDScalingwithGeomagneticLatitude
E
Σ=5S
Σ=500S
B
h
M≈ΣΕLh~Σ, Σ(λ=0)/Σ(λ=90)≈100
Cowlingeffect
DipEquator
ICDScalingwithGeomagneticLatitude
B
h E
I
HallConductancevs.GeomagneticLatitude
HAARP
ForPHF=800kWwegetMeff≈1011A‐m2atλ≈0 Meff≈3x1010A‐m2atλ≈6°
ForPHF=800KWM=1011A‐m2
M=3x1010A‐m2
ParametersallowustoconsideranequatorialbargebasingoftheHFtransmitter
BargeorShipboardOption
High Latitude
10MHz
1MHz
Equator
StrawmanHFArray
• HFfrequency5‐8MHz• Linearpolarization• Power on ship or self‐propelledplatform
4MHz
• Canprovidestrategicandtacticalsubcommunications
ELFMobileArrayPerformance• OptimalareaforMobileArrayalongMagnetic
Equator(greenband,within2ofromdipequator)• Powerrequirementsdependonlocation
– Example:Korea‐YellowSea
• 800KWsystemcanprovidedataratesinthetensofbit/sec
• Signalaslargeas5pTat40Hzormoreatrangeof3500km
• Typicalbackgroundnoiseat40‐80Hzis200‐500fT/Hz1/2
ELFSub‐Comm.DARPA‐STOBriefing13
800kWHFSystem5pTlineat40Hz
OptimalRegionForELFArray
EquatorialTestSystem• Simplified,lower‐costsystembasedonprovenHAARPdesign• Relocatableandeasilyexpandable‐‐canbeexpandedintooperationalTX
whentestsarecomplete• Fullymodular,designedforeasyrelocation
– transmittersintransportableshelters– antennasandgroundscreendesignedforsimplerelocation– minimalsitepreparation(concretefoundationsforantennas)
• UseexistinghighpowertubesasGFE(e.g.100kWOTH‐Btubes)– minorantennaandfeedmodificationsneeded
• Antennaisscaled,simplifiedversionofHAARPlowbandantenna– resizedfor5‐8MHz(abouthalfthesizeofcurrentHAARPantennas)– simplifiedinstallationandguidingsystemwithmodulargroundscreenorno
screen
8‐10montheffortto• DesignanequatorialHF‐ELFsystem
– Requirementsforsub‐comm.• Power,frequency(matchlocalionosphere),ELFgenerationefficiency,coveragearea,bitrate..
– Tradespace• Cost&performance:OTH‐Bsurplus(tube)vs.solidstate
– Cost&riskanalysis• Availability&usabilityofOTH‐Bequipments
– Sitesurvey&selection• Supportinginfrastructures,localpowergrid,landuse
• Developprogramwithoptions:– Cost,schedule,risksandmitigations– Go/NoGocriteriabetweenprogramphases
NextStep
• ELFproducedbyHAARPwithNOElectrojet–AMajorBreakthroughbasedondiscoveriesinrecentHAARPcampaignsunderMURI/ONRandBRIOCHE/DARPAprograms– PredictableandrepeatableELFgenerationupto50Hzondailybasis– Meff≈4x109A‐m2– Validatedtechnique:plasmacurrentsdrivenbyHFheatingintheF/Elayers– TechnologytransferabletolowlatituderegionswithrobustF&noE’Jet
• AnefficientIonosphericELFsourcethatcanbepositionedintheateronamobileplatform– Datarate>>FELFsystem
• Highersourcestrength– HighTRLlevelfortransitioning
SUMMARY
SupplementarySlides
Equatorial14x10‐3S/m
Auroral1.2x10‐3S/m
Comparisonofequatorialandauroralconductivities
ComparisonofEquatorialandAuroralElectricFieldsandcurrents
Equatorial
Auroral
TheDipEquator
