Collaborative Research on Novel High Power Sources for and Physics of Ionospheric Modification. MURI 2 3 Year REVIEW Feb. 10, 2016

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1 UCLA Collaborative Research on Novel High Power Sources for and Physics of Ionospheric Modification MURI 2 3 Year REVIEW Feb. 10, 2016 Thomas M. Antonsen University of Maryland 1

Ionospheric Modification (IM) Using HF Heaters The Need for Transportable Heaters The ionosphere controls the performance of critical DoD and civilian communications and navigation systems IM

2 Ionospheric Modification (IM) Using HF Heaters The Need for Transportable Heaters The ionosphere controls the performance of critical DoD and civilian communications and navigation systems IM research has identified new processes triggered by HF waves in the ionosphere that mitigate or enhance ionospheric effects. Led to new communication & navigation capabilities Transportable Heaters will provide: 1. Research capability to explore latitudes different than high latitudes currently explored 2. Proximity to relevant applications Polar Cap Scintillation Satellite Communicatio ns (SATCOM) Equatorial Ionization Anomalies Remote Sensing Magnetic Equator Auroral Irregularities Day Night Space Surveillance Radar Equatorial Plasma Bubbles Space Asset Control and Telemetry Mitigation/Control of Ionospheric Effects is a DoD Priority Global Positioning System (GPS) 2

3 Goals/Objectives of this MURI Develop prototypes of EM sources for transportable ionospheric heaters based on: Comprehensive understanding of the current status of Ionospheric Modification research and applications; Combination of theory/modeling with laboratory experiments scaled to simulate ionospheric plasma parameters at different geo magneticlatitudes. DevelopmentofmodernhighpowerRF source technology and antenna engineering using meta materials.

Why Transportable? Past IM experiments, conducted at high latitudes indicate strong dependence of ionospheric processes on geomagnetic latitude.

4 Why Transportable? Past IM experiments, conducted at high latitudes indicate strong dependence of ionospheric processes on geomagnetic latitude. Transportable heaters will allow for the first time a quantitative exploration of the IM requirements vs. geomagnetic latitude without expensive ground installations. Proximity to application (battlefield or else) a significant advantage (reduced ERP) HAARP Platteville Arecibo Jicamarca EISCAT Equator SURA 4

5 Impact of Transportable Heaters 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 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 5

6 Technology Challenge Transportable Heater HAARP size 300m by 400m Area 1/100 Array size 110 m by 70 m 1/20 Requires 16 MW to match* HAARP Effective Radiated Power * May not be necessary Issues: Frequency Tuning Power consumption/efficiency Antenna efficiency Polarization control 6

UCLA UMD Charge Particle Beams Thomas Antonsen* Brian Beaudoin Gregory Nusinovich Tim Koeth UCLA

7 Participating Team Members UMD Space Plasma Physics Dennis Papadopoulos* Gennady Milikh* Bengt Eliasson Xi Shao Texas Tech HPM Andreas Neuber* John Mankowski* Ravindra Joshi James Dickens UCLA UMD Charge Particle Beams Thomas Antonsen* Brian Beaudoin Gregory Nusinovich Tim Koeth UCLA Walter Gekelmann* Yuhou Wang Pat Pribyl + 20 Postdocs, Graduate and Undergraduate Students * Co PIs 7

8 Collaboration Structure / Technical Approach Specification of Radiated Power, ERP, Frequency, Polarization Papadopoulos UMD Theory/Modeling IM Research Status Ionospheric Physics Gekelman UCLA/LAPD Laboratory Experiments Physical limitations of Radiated Power, ERP, Frequency, Polarization Antonsen UMD Development of High Efficiency Inductive Output Tubes (IOT) Vacuum Tubes High Power RF Source Technology Antenna Research Solid State Physics Neuber Mankowski TTU Electrically Small Antennas Laser Triggered RF Switches (PCSS) 8

9 Consortium Accomplishments/Plans Identify Mid-Latitude IM Applications Verify Physics (theory and experiment) Determine Heater Requirements Develop Heater Technology - Sources - Antennas Time Line Accomplishments: CY: Short term plans: CY: 2016 Long term plans: CY:

IM Applications pp p ( ) 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 Identified

Plasma Ionospheric Layers Use HF Turbulence to create plasma (AIT) with density larger than the ionosphere Bi-static links at UHF and L-band Control trans-ionospheric communications paths Ionospheric

10 IM Applications pp p ( ) 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 Identified Mid-Latitude IM Applications magnetosphere Virtual Antennae at ELF/VLF - Communications Submarine communications, UUV control, Artificial Underground Plasma imaging, RBR Layers (APL) Artificial Plasma Ionospheric Layers Use HF Turbulence to create plasma (AIT) with density larger than the ionosphere Bi-static links at UHF and L-band Control trans-ionospheric communications paths Ionospheric Plasma outflows Turbulence & Create ducts 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 S F ELF/VLF PRN

11 Theory and Experiment Physics Verification 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 fieldaligned striations. Low Frequency Waves due to HF Heating of the Ionosphere Spread-F control using Transportable Heater induced heating Launched shear Alvén Waves 11

12 Technical Approach Laboratory Measurements Large Plasma Device (LAPD) UCLA Machine parameters chamber size 1 m diameter 20.7 m long discharge plasma parameters n e ~ cm -3 B 0 up to 3.5 kg, variable profile T e ~ 6 ev, T i ~ 1 ev Fill pressure ~ Torr afterglow plasma DC discharge, 1 Hz plasma parameters production repetition n e ~ cm -3 T e ~0.5 ev, T i ~0.1 ev 12

13 Virtual Antenna Ejet Virtual Antenna ICD CME Detection Artificial Turbulence Accomplishments: Heater Specifications Ion reg ion D/E F NA F Latitude Dip Equator Dip Equator Any appropri ate Dip Equator ERP dbw Rad. Power MW Gain dbi f MHz Polariz ation Modul ation Linear 10 khz Linear 200 Hz * O X TBD Space Radar Linear NA Ducts F Middle Latitude O NA Comments: Confidence ranking High, Moderate, Sub moderate 13

sources underneath 4 m Electrically Small Antennas 102

14 Identified Strawman Platform Requires: New Sources, Novel Antenna design 33 m 4 m Power supplies and sources underneath 4 m Electrically Small Antennas 102 m ( 1 MW generator ~33 m 3 14

ESA Antenna Concept Project Objective Development of an electrically small antenna, capable of ~ 1 MW cw power output, dielectric tuner tunable from ~ 3 to 10 MHz.

15 ESA Antenna Concept Project Objective Development of an electrically small antenna, capable of ~ 1 MW cw power output, dielectric tuner 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 15

New Source: PCSS 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

16 New Source: PCSS 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 blocking Understanding corroborated by experimental and simulation results. Limitations of bulk PCSSs Causes of device degradation. Limited photocurrent efficiency caused by relationship between deep level defects and the carrier recombination lifetime. Alternative Optical Sources Evaluation of non-laser light sources as alternative optical drivers as performance specifications allow. 16

New Technology: Grid-less IOT Magnetron Injection Gun with modulation anode

on collector Limiting current space charge limitations to energy extraction

17 New Technology: Grid-less IOT Magnetron Injection Gun with modulation anode Class 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 modulator Stackable design to reach 2.5 kev w 5ns rise time. Constant Impedance Transformer Capacitive tuning of air-core transformer maintains gap impedance. Design of gridded gun for prototyping 17

18 Current Year (2016) Plans Spread-F control by TH plasma injection and heater requirements Comprehensive analysis of Cerenkov based virtual antenna Space Physics 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 conduction Optimization of guard ring structure and device thickness PCSS 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 ESA Test prototype gridded gun with fast modulator Complete design and construction of constant impedance transformer IOT Generate RF with high efficiency Review MIG design with vendors submit DURIP 18

19 Long Term (2017, 2018) Plans TH requirements for supporting ground-based Radiation Belt Remediation schemes Explore utilization of X-mode F-region collisionless heating to remedy heating inefficiency in order to avoid inefficiency caused by gain limitations intrinsic to THs. Space Physics Characterization of PIN PCSS-DC Blocking, Switching, Photocurrent vs. wavelength, Photocurrent vs. optical power Evaluate PIN PCSS as modulator for IOTs PCSS Demonstrate PIN PCSS with ESA integration Further optimize PIN PCSS and characterize PIN PCSS Develop practical mutual inductance tuning Find optimum capacitive gap geometry Evaluate array performance at shorter spacing (antenna cross-talk) Drive antenna mockup with PCSS Evaluate antenna geometry for 10 MHz breakdown limits (few MW cw) ESA Drive antenna with PCSS, IOT or similar mock source Operate and characterize prototype Design and Purchase MIG gun IOT Operate (200 kw) source Develop requirements for 1MW source PCSS Modulation All: Address issues connected with transition of particular TH configuration to

20 Synergies Provide design input to the source development teams Ion reg ion Latitude ERP dbw Rad. Power MW Gain dbi f MHz Polariz ation Modul ation Virtual Antenna Ejet D/E Dip Equator Linear 10 khz Virtual Antenna ICD F Dip Equator Linear 200 Hz * CME Detection NA Any appropri ate O X TBD Space Radar Artificial Turbulence F Dip Equator Linear NA Ducts F Middle Latitude O NA 20

21 Antenna Design Meets Common traditional Requirements RF generator (IOT tube) coaxial cable Load/antenna 50 Ohms typically 377 Ohm Antenna has two jobs: Match coaxial cable impedance and radiate efficiently direct drive RF generator (PCSS) Load/antenna 377 Ohm Effective antenna input impedance more freely selectable Higher impedance allows relaxing switch on state resistance. 3/4/

overlap air tuning possible Increased dielectric requirement for

22 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) 2/10/

23 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 23

24 UCLA-DURIP 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 24

TTech DURIP: Ultra Short Pulse Laser System for Photoconductive Switch Advancement Key points: 100 fs pulse enables accurate measurement of recombination

25 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

26 Participating Team Members UMD SPP Dennis Papadopoulos Gennady Milikh Xi Shao Alireza Mahmoudian Bengt Eliasson Students Aram Vartanyan Chris Najmi Kate Zawdie Blagoje Djordjevich UCLA Walter Gekelmann Yuhou Wang Texas Tech Andreas Neuber John Mankowski James Dickens Ravindra Joshi Students Daniel Mauch Jacob Stephens Sterling Beeson David Thomas John Shaver Vincent Meyers Paul Gatewood Benedikt Esser UMD CPB Thomas Antonsen Brian Beaudoin Gregory Nusinovich Irv Haber Graduate Students Amith Narayan Jay Karakad Undergraduate Students Quinn Kelly Connor Thompson Charles Turner Nikhil Goyal Advisors Irv Haber John Rodgers Edward Wright 26

1 2 3 4 5 6 Texas Tech graduate research team: 1 Shannon Feathers, 2 Benedikt Esser,

27 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 27

28 UCLA Experimental Group Pat Pribyl Walter Gekelman Yuhou Wang 28

29 UMD Space Plasma Physics Dr. Gennady Milikh Professor Dennis Papadopoulos Dr. Xi Shao Dr. Surja Sharma Kate Zawdie A. Chris Najmi Dr. Aram Vartanyan Abhay Raina 29

30 Charged Particle Beam Team Tom Antonsen Brian Beaudoin Irv Haber Gregory Nusinovich Amith Narayan Jayakrishnan Karakkad Charles TurnerConnor Thompson Nikhil Goyal Quinn Kelly 30

Making 1 MW cw HF practical

Making 1 MW cw HF practical 4 to 10 MHz antenna ESA Electrically Small Antenna to interface with UMD 50 Ohm IOT rf source. - Factor of 5 to 10 smaller than dipole - Frequency tunability demonstrated High