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Collaborative Research on Novel High Power Sources for and Physics of Ionospheric
Modification
UCLA
Thomas M. AntonsenUniversity of Maryland
MURI 2‐3 Year REVIEW Feb. 10, 2016
Mitigation/Control of Ionospheric Effects is a DoD
Priority
Auroral Irregularities
Equatorial Plasma Bubbles
MagneticEquator
Day Night
Equatorial Ionization Anomalies
Remote Sensing
Polar Cap Scintillation Space Surveillance
Radar
Space Asset Control and Telemetry
Global Positioning System (GPS)
Satellite Communications (SATCOM)
Ionospheric Modification (IM) Using HF HeatersThe Need for Transportable Heaters
• The ionosphere controls theperformance of critical DoD andcivilian communications andnavigation systems
• IM research has identified newprocesses triggered by HF wavesin the ionosphere that mitigate orenhance ionospheric effects.
• Led to new communication &navigation capabilities
• Transportable Heaters willprovide:
1. Research capability to explorelatitudes different than highlatitudes currently explored
2. Proximity to relevant applications2
Goals/Objectives of this MURIDevelop prototypes of EM sources for transportableionospheric heaters based on:
Comprehensive understanding of the current status ofIonospheric Modification research and applications;
Combination of theory/modeling with laboratoryexperiments scaled to simulate ionospheric plasmaparameters at different geo‐magnetic latitudes.
Development of modern high power RF source technologyand antenna engineering using meta‐materials.
• Past IM experiments, conducted at high latitudes indicatestrong dependence of ionospheric processes on geomagneticlatitude.
• Transportable heaters will allow for the first time a quantitativeexploration of the IM requirements vs. geomagnetic latitudewithout expensive ground installations.
• Proximity to application (battlefield or else) a significantadvantage (reduced ERP)
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Why Transportable?
HAARP
Arecibo
EISCAT
Platteville
Equator
SURA
Jicamarca
Impact of Transportable Heaters
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New Applications• Virtual Antennae at ELF/VLF• Artificial Plasma Layers (APL)• Artificial Ionosph. Turbulence (AIT)• Bi‐static links at UHF and L‐band• Plasma outflows & ducts
Basic Science and Engineering• Improved understanding of ionosphere• New class of High‐efficiency RF sources• High voltage fast optically triggered switches for directed energy
• Novel high power antenna concepts for high power rf and microwave transmission
Technology Challenge – Transportable Heater
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HAARP size 300m by 400m
Array size 110 m by 70 m
Requires 16 MW to match* HAARPEffective Radiated Power * May not be necessary
Issues:Frequency TuningPower consumption/EfficiencyAntenna efficiencyPolarization control
1/20
Area 1/100
Participating Team MembersUMD Space Plasma PhysicsDennis Papadopoulos*Gennady Milikh*Bengt EliassonXi Shao
Texas Tech HPMAndreas Neuber*John Mankowski*Ravindra JoshiJames Dickens
UMD Charge Particle BeamsThomas Antonsen*Brian BeaudoinGregory NusinovichTim Koeth
UCLAWalter Gekelmann*Yuhou WangPat Pribyl
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UCLA
+ 20 Postdocs, Graduate and Undergraduate Students* Co‐PIs
Collaboration Structure / Technical ApproachPapadopoulos
UMDTheory/ModelingIM Research Status
GekelmanUCLA/LAPDLaboratory Experiments
High Power RF Source
TechnologyAntonsenUMD
Development of High Efficiency Inductive Output
Tubes (IOT)
Neuber Mankowski
TTUElectrically Small
AntennasLaser Triggered RF Switches (PCSS)
Specificationof Radiated Power, ERP, Frequency,Polarization
Physical limitations of
Radiated Power, ERP, Frequency,Polarization
Ionospheric Physics
Vacuum Tubes
Solid State Physics
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Antenna
Research
Consortium Accomplishments/Plans
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Time LineAccomplishments: CY: 2014-2015Short term plans: CY: 2016Long term plans: CY: 2017-2018
• Identify Mid-Latitude IM Applications• Verify Physics (theory and experiment)• Determine Heater Requirements• Develop Heater Technology
- Sources- Antennas
IM Applications
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Identified Mid-Latitude IM Applications
• Virtual Antennae at ELF/VLF - Communications• Artificial Plasma Layers (APL) • Artificial Ionospheric Turbulence (AIT)• Bi-static links at UHF and L-band• Plasma outflows & ducts
pp p ( )
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• Virtual Antennae at ELF/VLF – Drive currents in the ionosphere using modulated HF heating to inject ELF/ VLF waves into the Earth-Ionosphere waveguide & the magnetosphere
• Submarine communications, UUV control, Underground imaging, RBR
• Artificial Plasma Layers – Use HF to create plasma with density larger than the ionosphere
• Control trans-ionospheric communications paths • Ionospheric Turbulence – Create plasma density structures
• Crate scintillations as well as scatter VF/UHF signals • Plasma outflows & Ducts – Create channels along the magnetic field that guide VLF signals & inject plasma at higher altitudes
• Ground-to-RB VLF injectiong (RBR); stabilize S-F • Create Bi-static G-to-G paths at UHF/VHF – Create structures with scale size of the order of the UHF-VHF that can Bragg scatter communication links
ELF/VLF
PRN 7
S‐F”
Physics Verification
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Theory and Experiment
•Physics of artificial ionization and of heater excited upper hybrid turbulence•HF wave propagation and induced ionospheric turbulence in the magnetic equatorial region. •Anomalous absorption of O mode waves on magnetic field-aligned striations. •Low Frequency Waves due to HF Heating of the Ionosphere•Spread-F control using Transportable Heater induced heating•Launched shear Alvén Waves
Technical Approach – Laboratory Measurements
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Large Plasma Device (LAPD)
Machine parameters
chamber size 1 m diameter 20.7 m long
discharge plasma parameters
ne~ 3 1012 cm-3
B0 up to 3.5 kG, variable profile Te~ 6 eV, Ti~ 1 eV
Fill pressure ~ 5 10-5 Torr afterglow plasma parameters
ne~ 5 1011 cm-3
plasma production
DC discharge, 1 Hz repetition
Te~0.5 eV, Ti~0.1 eV
UCLA
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Ionregion
Latitude ERPdBW
Rad.Power MW
GaindBi
fMHz
Polarization
Modulation
Virtual AntennaEjet
D/E Dip Equator
65 1 5 4‐8 Linear 10 kHz
Virtual Antenna
ICD
F Dip Equator
74‐77 5‐10 7 4‐10 Linear 200 Hz *
CME Detection
NA Any appropri
ate
80‐85 4 15‐20 20‐100 O‐X TBD Space Radar
Artificial Turbulence
F DipEquator
77 10 7 4‐10 Linear NA
Ducts F Middle Latitude
77 10 7 4‐10 O NA
Comments: Confidence ranking High, Moderate, Sub‐moderate
Accomplishments: Heater Specifications
Identified “Strawman Platform”
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102 m
33 m
4 m
Power supplies and sources underneath
4 m
(http://nationalpowersupply.com/) 1 MW generator ~33 m3
Electrically Small Antennas
Requires: New Sources, Novel Antenna design
ESA Antenna Concept
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Project Objective Development of an electrically small antenna,capable of ~ 1 MW cw power output, tunable from ~ 3 to 10 MHz.Accomplishments•Experimental verification of antenna concept and tuning capability at 100 MHz (30 MHz to 100 MHz)•Experimental demonstration of full size antenna at 10 MHz (limited tuning range from 9.5 to 10 MHz)•Verified conventional antenna drive (sinusoidal source through 50 Ohm coax) •Verified direct drive approach•Radiated ~ 500 W at 10 MHz with approx. 90% efficiency (relative to DC power input)•Transportable “HAARP” scale‐up prediction
dielectric tuner
New Source: PCSS
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• Experimental demonstration of bulk Photoconductive Semiconductor Switch (PCSS) high power switching single shot (26 MW) and burst rep-rate (4 MW at 65 MHz)
• Physics of bulk Photoconductive Semiconductor switch (PCSS) conduction spatial illumination profile, optical wavelength, and optical power
• Physics of bulk PCSSs high voltage blockingUnderstanding corroborated by experimental and simulation results.
• Limitations of bulk PCSSsCauses of device degradation. Limited photocurrent efficiency caused by relationship between deep level defects and the carrier recombination lifetime.
• Alternative Optical SourcesEvaluation of non-laser light sources as alternative optical drivers as performance specifications allow.
New Technology: Grid-less IOT
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• Magnetron Injection Gun with modulation anodeClass D operation, annular beam leads to high efficiency and reduced demands on collector
• Limiting current space charge limitations to energy extraction from beam
• Fast Grid/Mod-Anode modulatorStackable design to reach 2.5 keV w 5ns rise time.
• Constant Impedance TransformerCapacitive tuning of air-core transformer maintains gap impedance.
• Design of gridded gun for prototyping
Current Year (2016) Plans
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• Spread-F control by TH plasma injection and heater requirements • Comprehensive analysis of Cerenkov based virtual antenna• Mid-latitude ICD virtual antenna for submarine communications• Artificial Ionization by TH at mid-latitude• Examine experiments indicative of F-region X-mode collisionless heating• Design PIN (p-type, intrinsic, n-type) PCSS structure
TCAD simulation of blocking and conductionOptimization of guard ring structure and device thickness
• Fabrication of PIN PCSS• Intermediate Step PIN PCSS characterization• Verify tuning methods that worked in 3 to 10 MHz mockup with full-size antenna• Verify matching approach with full size antenna• Test prototype gridded gun with fast modulator• Complete design and construction of constant impedance transformer• Generate RF with high efficiency• Review MIG design with vendors – submit DURIP
Space Physics
PCSS
ESA
IOT
Long Term (2017, 2018) Plans
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TH requirements for supporting ground-based Radiation Belt Remediation schemesExplore utilization of X-mode F-region collisionless heating to remedy heating inefficiency in order to avoid inefficiency caused by gain limitations intrinsic to THs.Characterization of PIN PCSS-DC Blocking, Switching, Photocurrent vs. wavelength, Photocurrent vs. optical powerEvaluate PIN PCSS as modulator for IOTsDemonstrate PIN PCSS with ESA integration Further optimize PIN PCSS and characterize PIN PCSSDevelop practical mutual inductance tuningFind optimum capacitive gap geometryEvaluate array performance at shorter spacing (antenna cross-talk)Drive antenna mockup with PCSSEvaluate antenna geometry for 10 MHz breakdown limits (few MW cw)Drive antenna with PCSS, IOT or similar mock sourceOperate and characterize prototypeDesign and Purchase MIG gunOperate (200 kW) sourceDevelop requirements for 1MW source PCSS ModulationAll: Address issues connected with transition of particular TH configuration to 6.2.
Space Physics
PCSS
ESA
IOT
Synergies• Provide design input to the source development teams
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Ionregion
Latitude ERPdBW
Rad.Power MW
GaindBi
fMHz
Polarization
Modulation
Virtual AntennaEjet
D/E Dip Equator
65 1 5 4‐8 Linear 10 kHz
Virtual Antenna
ICD
F Dip Equator
74‐77 5‐10 7 4‐10 Linear 200 Hz *
CME Detection
NA Any appropri
ate
80‐85 4 15‐20 20‐100 O‐X TBD Space Radar
Artificial Turbulence
F DipEquator
77 10 7 4‐10 Linear NA
Ducts F Middle Latitude
77 10 7 4‐10 O NA
Antenna Design Meets Common Requirements
3/4/2016 21
RF generator(IOT tube) coaxial cable Load/antenna
traditional
377 Ohm
Antenna has two jobs:Match coaxial cable impedance and radiate efficiently
50 Ohms typically
RF generator(PCSS) Load/antenna
direct drive
377 Ohm
• Effective antenna input impedance more freely selectable• Higher impedance allows relaxing switch on‐state resistance.
Horizontal Gap• University of Maryland suggested
modification• Larger gap possible due to increased
capacitive area• Tunable by adjusting area of overlap
– air tuning possible• Increased dielectric requirement for
breakdown mitigation (large volume, high quality dielectric needed)
222/10/2016
PCSS drive for MW IOT
• 1 MW average power RF requires 4 MW Peak Power MIG• Prototype MIG 70 kV-15 A Requires 2.5 kV mod-anode swing• 4 MW MIG Parameters: 100 kV - 40 A 4.5 kV mod-anode
swing
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UCLA-DURIP
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Intent : To purchase microwave hardware ( arbitrary waveform generator, high power amplifier, mixers...)! to enable launching tailored microwave waveforms (swept amplitude/frequency)!And measure E,B with a hetrodyne system
TTech DURIP: Ultra‐Short Pulse Laser System for Photoconductive Switch Advancement
Key points:• 100 fs pulse enables accurate measurement of recombination lifetimes• 2 orders of magnitude higher rep‐rate than currently available• Significantly improved photonic to rf conversion efficiency• Direct rf UWB source driver
Participating Team Members
UMD SPPDennis PapadopoulosGennady MilikhXi ShaoAlireza MahmoudianBengt Eliasson
StudentsAram VartanyanChris NajmiKate ZawdieBlagoje Djordjevich
Texas TechAndreas NeuberJohn MankowskiJames DickensRavindra Joshi
StudentsDaniel MauchJacob StephensSterling BeesonDavid ThomasJohn ShaverVincent MeyersPaul GatewoodBenedikt Esser
UMD CPBThomas AntonsenBrian BeaudoinGregory NusinovichIrv Haber
Graduate StudentsAmith NarayanJay Karakad
Undergraduate StudentsQuinn KellyConnor ThompsonCharles TurnerNikhil Goyal
AdvisorsIrv HaberJohn RodgersEdward Wright
UCLAWalter GekelmannYuhou Wang
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Texas Tech graduate research team: 1‐ Shannon Feathers, 2‐Benedikt Esser, 3‐Jacob Stephens, 4–David Thomas, 5‐Vincent Meyers, 6‐John Shaver, 7–Daniel Mauch
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2 3 4 5 6
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UCLA Experimental Group
Pat Pribyl Walter Gekelman Yuhou Wang
UMD Space Plasma Physics
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Professor Dennis PapadopoulosDr. Gennady Milikh
Dr. Xi Shao
A. Chris NajmiKate Zawdie Dr. Aram Vartanyan Abhay RainaDr. Surja Sharma
Charged Particle Beam Team
Amith Narayan
Connor Thompson Quinn KellyCharles TurnerJayakrishnan KarakkadNikhil Goyal 30
Tom Antonsen Brian Beaudoin Irv Haber Gregory Nusinovich