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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