Plasma and Electro-Energetic

Physics 16 March 2011

Dr. John Luginsland

Program Manager

AFOSR/RSE

Air Force Office of Scientific Research

AFOSR

Distribution A: Approved for public release; distribution is unlimited. 88ABW-2011-0756

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2010 AFOSR SPRING REVIEW2301E PORTFOLIO OVERVIEW

NAME: John Luginsland

BRIEF DESCRIPTION OF PORTFOLIO:

Explore scientific opportunities in plasmas and electro-energetic

physics where electromagnetic energy can provide new vistas in

high-power electronics, plasma-enabled chemistry, and

fluid/turbulence dynamics arenas

SUB-AREAS IN PORTFOLIO:

•High power microwave (HPM) sources (35%)

•Non-equilibrium plasma physics (44%)

•Pulsed power physics (21%)

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Plasma and Electro-Energetic Physics

WHY PLASMA?

The Air Force requires:

• Electronic attack & non-lethal

weaponry

• Electronic warfare

• Long range, high resolution radar

• Long range, large bandwidth

communications

• Compact chemical reactors (e.g.

ozone)

• Plasma combustion (higher fuel

efficiency, lower emission)

• Counter-directed energy

• Flight dynamics

• Turbulence control

• Ionosphere science (heaters)

ADS

TPI@USC

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Plasma and Electro-Energetic Physics

• Understand, manage, and engineer the intensity and energy density associated with electromagnetic fields and ionized materials in ways to produce useful work

– “Surface science” is extremely important

• Inherently multi-scale (and multi-physics)

– Develop and exploit modeling where we can

• Develop understanding and control of energy flow in plasma processes to maximize utility, efficiency, and compactness (thermodynamics)

• Recognize and exploit new areas where EM energy provide novel chemistry

– Plasma chemistry where Te >> Ti ~ Tgas

Scientific Challenges

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Non-Equilibrium Plasmas

• Plasma and electro-energetic physics portfolio

has the charter to understand and manage the

high energy density associated with materials in

the plasma state and the associated radiation

fields

• Three main focus areas:

– High power microwave sources

– Non-equilibrium plasmas sources

– Pulsed power drivers

• In addition to the inherent non-equilibrium

processes in the plasma, the real world typically

requires boundaries (materials) with their own

set of time/length scales

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High Energy Density Physics

• High Energy Density + Multi-Scale = non-equilibrium processes

– “Your mother told you to avoid nonlinear, multi-variable, time-dependent problems…”

2x700MW continuous

~GW for short periodsWikipedia Commons License

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Plasma - why it’s hard…

Maxwell’s Dynamical Equations (with complex surfaces):

Relativistic Lorentz Force Law for

relativistic momentum p and velocity u:

tDcJcH

tBcE

/)/1()/4(

/)/1(

HB

ED

BucEcqddp )/(/

Subject to the

initial value constraints:

4

0

D

B

With macroscopic media

(complex, dispersive):

“7D,” nonlinear, electro-dynamics & statics, relativistic

statistical mechanics, self-DC and AC fields, and QM

Source ,J

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“Tyranny of Scales”

L=nm-m L=m

T=fs-ps

T=ms-CW

Relativistic Klystron Oscillator (RKO)

L=cm=l

t = 50 ns

Mode Competition (Spatial Filter)

P(AU)

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Magnetron (Er x Bz)

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Fundamental Limits - Pf2

• Qiu et. al., “Vacuum Tube Amplifiers.” IEEE Microwave

Magazine, December 2009.

Pf2 is a fundamental limit for

vacuum electronics, HPM,

accelerators, and fusion

drivers

Pf 2 V 2 /l2 (V /m)2 E 2

P V 2 /Z; fl c

USAF constraint - size

AFRL/RD Magnetron Oscillator

AFRL Gyrotron Oscillator

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Advanced Magnetron – New Geometry

• Freq limits – From standard theory (# of

cavities; diameter vs l; cavity depth vs l)

• Er x Bz -> V(theta)

• Ez x Br -> V(theta)

• Enabled by 3D PIC

– Shows promise in 100s of GHz

Gilgenbach et. al., U-Michigan-Patent

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Enabling Technology: Modeling

• Magnetrons are WW2 technology that

we can still improve in revolutionary

ways… How?

• 3D, high-fidelity, parallel modeling of

high energy density fields and

particles in complex geometry with

some surface effects

Courtesy M. Bettencourt,

AFRL/RDH

“Bumpy” Magnetron with ICEPIC

1.0

0.0300 500V(kV)

P(A

.U.)

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Carrier-field Dynamics at High Frequency (100-1000 GHz)

Ensemble MC + FDTD in Si

Willis, Hagness,

Knezevic, 2010

UWisconsin

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Amplifiers vs Oscillators A Grand Challenge

94 GHz, 80kW (10kW ave),

700MHz BW, 7.1e8 W-GHz2

110 GHz, 1MW (10s pulse),

1.1 MHz BW, 1.2e10 W-GHz2

Haystack

ITER/D3D

Enabling technology for

HP waveform diversity

and adaptive EM

(DDDAS)

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Single Modes in 3D Devices(MM and PBG)

Modern EM structures

to provide single mode

operation

140GHz Gyrotron@MIT (Temkin)Ka-Band Maser@Ustrathclyde (Cross)

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What can you do with 1-10eV e-? (by Plasma Thermodynamics)

• Plasma guide stars, sensors, and light sources

• Active control of EM

• Combustion (ignition, soot)

– Novel neutral/plasma chemistry

• Learning how to perform controlled ionization at

high pressure (thermodynamics and modeling) TPI@USC

Mauna Kea Telescopes

Hopwood TPS, 03 (1W@ 20,760 Torr)

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High Frequency Breakdown Science(Transition)

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Kinetic Global Model(Transition)

0.1 1 10 100 10000.1

1

10

100

(n

s)

Pressure (Torr)

PIC/MC

GM (Maxwellian)

GM (EEDF with x = 6.5)

xcecf

22/1

1 )(

decm

e K

ion

xc

ion

ePICion

22/1

1)(2

From PIC:

Assume general distribution function:

Argon GasEo = 2.82 MV/mf = 2.85 GHz

Solve continuity, energy, and power

absorption equations for each

species

Get x for distribution function from

PIC: Good over 4 orders in

pressure!

Works for all gases tried – shape

depends only on cross sections

Verboncoeur – UCB/MSU

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Enabling Technology: Modeling

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Plasma Pencil (Tgas << Te)(Transition)

ODU, USC, CWRU,UC-B/MSU

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Basic Physics of Electrical Energy Storage

• Typical HPM Cap

– 0.11-0.18 J/cc

• Discharge rate, breakdown

strength vs. high dielectric

– Fundamental challenges

• AFRL is looking at ceramics

and nonlinear dielectrics

(ferro and para-electric

materials)

• Other research

– Novel “super”-capacitors

• Fast discharge battery

McDougall, PPC 09

AFRL

STTR

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Advanced Dielectrics Science

• Engineer materials to provide

competing characteristics of

– Energy density ()

– Rapid discharge capability

– Breakdown Dielectric

strength (E)

– Engineered non-linearity

(Ferro- and Anti-Ferro-

Electric)

• Ceramic BST is one candidate

(nano-powder)

– Grain size determines

strength

• 25 m -> 3.5 m

• 25 kV/cm -> 85 kV/cm

• Novel Circuits

Model of BaTiO3 slab

QM to EM theory to circuits in the lab

Nonlinear Transmission Line & SchematicTime (ns)

Vo

ltag

e(k

V)

1 2 3 4 5 6

0

50

100

150

200

250

300

z = 0 cm

z = 10 cm

z = 20 cm

z = 30 cm

z = 40 cm

z = 50 cm

z = 60 cm

Gaussian TEM Pulse in Coaxial Waveguide - Nonlinear Dielectric

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Electro-Energetic PhysicsMajor Research Topics

• High Power Microwave Sources

– High Power Amplifiers

– Raw Peak Power Oscillators

• Non-equilibrium Plasma Physics

– Modeling of dense, kinetic plasmas

– Micro-plasma

• Pulsed Power Physics

– Dielectric Strength Physics

– Compact, Portable Pulsed Power

– Plasma switches

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Other Organizations

• DARPA (T. Akinwande, novel phase contrast x-rays and D. Purdy,

Atmospheric plasma sources)

• DTRA (John Les, C-HPM and EMP)

• ONR (Peter Morrison, C-HPM)

• ARL (H. More, C-HPM)

• NRL (T. Mehlhorn, J. Schumer Space plasma, inductive pulsed

power)

– Ties to AFRL

• DOE Office of Science (A. Satsangi, low-T plasma)

• NSF (S. Gitomer, A. Atreya , low-T plasma, combustion)

• Plasma lunch…

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Summary of Recent Transitions

• Global plasma models (UCB to

AFRL/RD)

• 3D Cathode modeling (Rutger’s

to AFRL/RD)

• Air breakdown science at high

frequency (MIT to AFRL/RD)

• STTR (Wargaming to Air

University & CNO SSG; Novel

dielectrics to RZ; NLTL design

to RD)

• Pulsed power systems (USC to

AFRL/RB and NIH)

MAP@ASBC