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1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To)29-08-2007 Final Performance Report 1 Dec 2003 - 31 May 2007

MEASUREMENT OF ATMOSPHERIC PRESSURE AIR PLASMA VIA 5a. CONTRACT NUMBER

PULSED ELECTRON BEAM AND SUSTAINING ELECTRIC FIELD5b. GRANT NUMBER

FA9550-04-1-0015

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S) 5d. PROJECT NUMBERRobert J Vidmar and Kenneth R Stalder

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORTNUMBER

University of Nevada, RenoSponsored Projects, Mail Stop 3251664 N Virginia StreetReno, NV 89557-0240

9. SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORIMONITOR'S ACRONYM(S)

AF Office of Scientific Research AFOSR/NE4015 Wilson Blvd, Room 713Arlington, VA 22203-1954 11. SPONSOR/MONITOR'S REPORT

-> Y- V ojwb ek& P )l K %rFR -S-r(TW0 -0 312. DISTRIBUTION / AVAILABILITY STATEMENT '-RARTO 3 8UNLIMITED 4 AtTfA

13. SUPPLEMENTARY NOTES

14. ABSTRACTAn apparatus to study the generation of plasma in air was designed, fabricated, and

assembled. A 400-liter test cell was developed to study plasma in air which has a pressurethat can be varied from standard atmospheric pressure at sea level to 1 mTorr at 300,000 ft.Plasma is generated by impact ionization of air due to bombardment by a 100-keV electronbeam. Microwave diagnostics quantify electron number density and optical diagnosticsquantify ozone production. A particle in cell plasma code (MAGIC) and an air-chemistry codeare used to quantify beam propagation through an electron-beam transmission window into airand the volumetric ionization rate within the test cell. Sensors were developed to monitorbeam current incident on a transmission window and the resulting plasma formed in air on thetransmission side of the window. Diagnostics from multiple sensors are acquiredsimultaneously for studies of power required to generate and maintain plasma in air on thetimescale of 1 ms.

15. SUBJECT TERMSAir Chemistry, Air Plasma, MAGIC Modeling, Plasma, Power, Test-Cell

16. SECURITY CLASSIFICATION OF: UNCLASSIFIED 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON

OF ABSTRACT OF PAGES Robert J Vidmar

a. REPORT b. ABSTRACT c. THIS PAGE UNCLASSIFIED 19b. TELEPHONE NUMBER (include area

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UNLIMITED 25 code) 775 682-9742

Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18

Final Performance Report 29 Aug 2007

MEASUREMENT OF ATMOSPHERIC PRESSURE AIR PLASMA VIAPULSED ELECTRON BEAM AND SUSTAINING ELECTRIC FIELD

By: ROBERT J VIDMAR

Prepared for:

AIR FORCE OFFICE OF SCIENTIFIC RESEARCH4015 WILSON BOULEVARD, ROOM 713ARLINGTON, VA 22203-1954

CONTRACT NUMBER: FA9550-04-1-0015

Approved for Public Release: Unclassified with Distribution Unlimited

20070917134

University of Nevada, Reno1664 North Virginia StreetReno, Nevada 89557-0240 USA

ABSTRACT

An apparatus to study the generation of plasma in air was designed, fabricated,and assembled. A 400-liter test cell was developed to study plasma in air which has apressure that can be varied from standard atmospheric pressure at sea level to 1 mTorrat 300,000 ft. Plasma is generated by impact ionization of air due to bombardment by a100-keV electron beam. Microwave diagnostics quantify electron number density andoptical diagnostics quantify ozone production. A particle in cell plasma code (MAGIC)and an air-chemistry code are used to quantify beam propagation through an electron-beam transmission window into air and the volumetric ionization rate within the test cell.Sensors were developed to monitor beam current incident on a transmission windowand the resulting plasma formed in air on the transmission side of the window.Diagnostics from multiple sensors are acquired simultaneously for studies of powerrequired to generate and maintain plasma in air on the timescale of 1 ms.

CONTENTS

ABSTRACT ii

I INTRODUCTION 1

II TECHNICAL 2A. Air Plasma Test Cell 2B. Electron-Beam Source 3C. Transmission Window 4D. MAGIC Modeling 5E. RF Diagnostics 6F. Ozone Detection 7G. Multichannel Simultaneous Data Acquisition 7

III RESULTS 8A. Complete Facility 8B. Multichannel Data Acquisition 8

IV PERSONNEL, INTERACTIONS, AND PUBLICATIONS 12

REFERENCES 14

APPENDIXMAGIC TEST CELL GEOMETRY A-2MAGIC DIAGNOSTIC DATA A-3

III~o

FIGURES

1. Upper flange of test cell. 22. Main body of test cell. 63. Installed test cell with specifications. 94. High-voltage rack and electron gun mounted to upper flange of test cell. 115. Transmission window and current sensors. 126. Mesh sensor mounted in Teflon insulator connected to brass feedthrough. 137. Aluminum transmission window loaded with atmospheric pressure. 138. Mid plane ionization rate, beam current, and radial distribution. 139. RF horn mounting fixture detail. 13

10. Time domain S12 of internal reflections at 10 GHz with absorber. 1411. White cell mounted in air-plasma test cell for ozone measurement.12. Hamamatsu H5783-03 mount and filter housing.

TABLES

1. Multichannel diagnostics. 10

iv

I INTRODUCTION

The overall goal of investigating the power required to generate and sustainelectron-beam produced plasma in air was advanced with an apparatus designed tostudy power and air chemistry issues. The apparatus consists of an electron-beamsource, a transmission window system, an air-plasma test cell, RF diagnostics, opticaldiagnostics, and a data acquisition system. The apparatus progressed from concept,specifications, component orders, assembly, testing, and refinement.

The overall investigation of electron-beam generated air plasma resulted in thedevelopment of an air plasma test cell integrate with an electron beam source,diagnostics, and an air-chemistry simulation code. This instrument and the associatedcontrols and diagnostics provide an apparatus to quantify air-plasma generation in airwith a pressure ranging from 1 mTorr to 760 Torr. At the start of this project there wasan empty laboratory. An air-plasma test cell was designed, fabricated, and installed.An electron beam source was specified ordered and installed. To port the electron guninto the test cell a transmission window and beam current monitoring system wasdesigned and installed. Beam propagation through the transmission window into air ismodeled using MAGIC, a PIC plasma simulation code from ATK Technologies. An air-chemistry code is used to convert beam current estimates in the test cell to electrondensities and air species concentrations. RF diagnostics and an ozone detectionsystem were developed and installed.

Nonequilibrium plasma has been theoretically estimated by Vidmar (1990) torequire less power to generate and sustain than a plasma in thermal equilibrium. Theexperimental work of Macheret et al (2001) for ambient air at 700 K, Adamovich (2001)for optically pumped CO/Ar/0 2 and CO/Ar/N2 mixtures at 700 K, Yu et al (2002) for air at2,000 K, and Stark and Schoenbach (2001) for air at 2,000 K consistently demonstratethat a nonequilibrium plasma requires less power for bulk gas temperature significantlyabove ambient. The electron beam air-plasma apparatus has the capability to generatea nonequilibrium plasma for which the bulk gas remains at ambient temperature.

The DoD has found air plasma applications ranging from coating of implants,plasma surgery, bio-decontamination, hydrodynamic flow control on aerodynamicsurfaces, supersonic shock-wave mitigation, plasma assisted combustion in aircraftengines, RF effects, and agile plasma mirrors. These applications cover the range ofaltitudes from sea level to 300,000 ft with electron densities from 1010 to 1013

electrons/cm 3. Electron beam plasma generation is the most efficient system knownrequiring an average expenditure of 34 eV per electron-ion pair. Preheating of air isunnecessary and air temperature for short pulses remains at the ambient airtemperature. For large volumetric and airborne applications electron-beam ionizationcan fill large volumes and large angle scattering in air provides a means of fillingirregular shapes and regions not directly exposed to the electron beam. The plasmagenerated is generally nonequilibrium where the bulk gas temperature remains nearambient and the electron temperature is many times larger.

1

II TECHNICAL APPROACH

A. Air Plasma Test Cell

The air-plasma test cell was designed to facilitate a wide range of diagnostics andaccommodate 1 mTorr to 760 Torr operation, as well as high vacuum to facilitatecalibration of the electron gun source and leak detection. The drawings in Fig. 1 and 2quantify the design which anticipated a number of ports of different diameters positionedon the midplane of the test cell. These ports are currently populated with equipmentdevoted to RF diagnostics, laser absorption spectroscopy, emission spectroscopy,ozone absorption spectroscopy, and mass spectroscopy. The installed test cell withannotated specifications appears in Fig 3.

0 0 € + +

0 13. 0' 12.0" 0 44.0" OD.....

0_ °+° + + .. ++

TOPSIDE BO'rFOM

Figure 1. Upper flange of test cell.

Optical EmissionsL .o

1101,• + + + + + 0

A 0 . . .3 ,.F I SO-200

2 00 + + + +

Hiden Ana o 3100 Spa.

240° [IF Rf 1114 ... ".1 J• -.. ' • 1--- /i 2700

290° SpareII ~ ITOPSIDE SIDE BOTTOMFigure 2. Main body of test cell.

The port specifications noted in Fig 2 have evolved since the fabrication of the test

cell. RF diagnostics are between the ports at 00 and 1800, an a mass spectrometer isbeing attached to the port at 2700. The cell sits on a sturdy stand with vacuum pumps

2

INSIDE DIAMETER: 36", 91.44 cm 6" CF ELECTRON GUN PORTSINSIDE HEIGHT: 24", 60.96 cm 100 KV, 10 maVOLUME: 24,430 In3, 400.4 literSURFACE: 4,750 In 2, 3.065 m2

PORTS ON 4 1/2" CFCIRCUMFERENCE SPA2EC8 CFSPARES

2 6" CF6 4 112"1 CF4 2 3/4"1 CF

8" CF NIPPLERF DIAGNOSTICS 4 1/2" CF

QUARTZWINDOW

Figure 3. Installed test cell with specifications.

directly below. An I-beam and chain-hoist system were installed in the air-plasma laboratory to facilitate removal of the electron gun, lead shielding, and upperflange, which together exceeded 700 Ibm.

B. Electron-Beam Source 3

An electron beam source was specified and procured from Kimball Physics ofWilton, NH. The unit in Fig. 4 is a custom design and has now become a productreferred to as a EGH-8201 Electron Gun and EGPS-8201 power supply. The electrongun is operated at an energy of 100 kV with a maximum beam current in excess of 20ma and arbitrary pulse generation with 100 ns rise/fall time. In normal operation the endof the electron gun is sealed off with a transmission window to keep the vacuum in theelectron gun below 10-7 Torr. Initial operation of the electron gun had a high level ofmaintenance and repair as many components failed due to spurious current surges inthe electron gun while performing high-voltage conditioning. A problem arose at 50 kVthat necessitated return of a high voltage junction box to Kimball to replace a high-voltage isolation transformer and associated components. Approximately 100 Ibm oflead shielding is used around the perimeter of the electron gun and so reduces thebackground radiation level to approximately twice background above the perimeter ofthe 44 in upper flange. One meter further away from the flange are operating consoleswhere the background radiation remains normal during operation.

3

)MA"

Figure 4. High-voltage rack and electron gun mounted to upper flange of test cell.

One major shortcoming of the EGH-8201 Electron Gun and EGPS-8201 powersupply is the beam current monitoring design, which is for steady state operation. Formicrosecond and millisecond operation the Kimball current meters that monitor currentflow from a high-voltage power supply do respond quickly enough. For short pulses thecharge involved is a small fraction of the charge stored within the high-voltage cabling ofthe system. A solution for real-time current monitoring is addressed in the next section.

4

C. Transmission Window

The porting of an electron beam from the source through a transmission window issketched in Fig. 5. The electron beam passes through a 60-mm aperture that definesthe maximum beam diameter downstream. The beam then impinges on a nickel meshwith 98% transparency that is mounted in a Teflon insulator. Part of the beam isstopped by the mesh and so provided a signal that is proportional to the beam current.Most of the beam continues and passes through an aluminum honeycomb covered witha thin aluminum foil. The foil honeycomb and 0-ring seals (not shown in Fig. 5) arecompressed with an aluminum clamping ring with mounting bolts insulated from ground.The overall signal associated with the foil window consists of the current stopped by thefoil and honeycomb plus the current associated with secondary electron generation onthe foil and honeycomb and the shunt resistance from the foil surface to groundassociated with the air plasma.

ALUMINUM HONEYCOMB INCIDENT VACUUM FOR ELECTRON BEAMSUPPORT AND ALUMINUM ELECTRONS 5 X 10-8 Torr to 7 X 10-7 TorrTRANSMISSION WINDOW - 100 keV

25 im (1.0 mil)17 umn (0.7 mil)12 ~ni (0.5 mil)

NICKEL MESH98% TRANSMISSION APERTURE PLATE

dE 60-mm 10SIGNALS FROM UV "N"oiGRAPHITE PLATE OPTICAL BSE PRESSUREINFOIL WINDOW FIBER AIR-PLASMA TEST CELLAND MESH BE 760 Torr (Sea Level)

ISO Torr (30,000 ft)S1 I mTorr (300,000 ft)

. . .... .•I[ E. .... ........... ..

-- I-

I ISEE Y I. dE TEFLON INSULATOR

ENERGY DEPOSII-- WITH 2% NICKEL MESHAND OPTICAL EXCITATION (CLAMPING ASSEMBLY

OF AIR NOT ILLUSTRATED)

STRONG LINES EXCITED IN NITROGEN SE SECONDARY ELECTRONS

N 2 SECOND POSITIVE, N 2 (C 3 1 '- B3r11), 337.1 nm BSE BACKSCATTERED ELECTRONSN2+ FIRST NEGATIVE, N +(B 2 Nr• - X2 o), 391.4 nm

SSE3 SE

GRAPHITE PLATE

Figure 5. Transmission window and current sensors.

The 2-mil nickel is visible in Fig. 6 as well as the honeycomb structure on theopposite side of the Teflon insulator and the bottom side of an aluminum clamping ring.

5

The electrical connection for the mesh is made through the Teflon ring and sealed withthe brass electrode visible in Fig. 6. This assembly is turned upside down and atransmission window foil is placed over the honeycomb and sealed with an O-ringbetween the Teflon and the foil.

Figure 6. Mesh sensor mounted in Teflon insulator connected to brass feedthrough.

The 1-mil aluminum transmission window foil made from Alloy 1100-0 shown inFig. 7 is held in place with an aluminum clamping ring which is bolted to the lowersurface of the upper flange in Fig. 1 and 3. The electron gun is mounted on theopposite side of the upper flange and evacuated to a high vacuum for electronacceleration. The honeycomb provides mechanical support against the loading due toatmospheric pressure. The mechanical design has been tested with atmosphericpressure loading for hundreds of hours without any sign of honeycomb failure.

Transmission window failures have occurred due to overheating the foil whichresults in a pinhole leak. Aluminum foils of alloy 1100-0 in thicknesses of 0.75 mil and0.50 mil have been tried but stress related pinholes appeared several days afterevacuation. These failures suggest that a material with high tensile strength wouldsurvive. Aluminum alloys 2024-T3, T4, T351, and T361 and 5052-H32, H34, H36, andH38 have tensile strengths between 5 and 10 times that of alloy 1100-0. Obtaininghigher strength alloy foils is difficult.

6

" I

Figure 7. Aluminum transmission window loaded with atmospheric pressure.

In operation the system is calibrated with the honeycomb and foil removed and agraphite plate with a fluorescent coating placed on the bottom of the air-plasma test celland insulated from ground. The system is evacuated and pumped to approximately 1.5x 10-7 Torr. The electron source is operated in a pulsed mode and the mesh voltageand graphite plate signal developed across load resistors are monitored as a function ofelectron source operating parameters: filament voltage and current. The graphite platecaptures all the current flowing through the mesh and the optical pattern on the graphiteplate confirms the beam is confined to a circular pattern on the plate.

The honeycomb and foil are installed. The mesh signal is then used to determinethe beam current incident on the honeycomb and foil. The subsequent propagation ofelectrons through the foil into the test cell is modeled using a computational particle incell code.

D. MAGIC Modelinq.

A particle in cell simulation program from ATK Mission Research commonly calledMAGIC was used to simulate the passage of electrons through the transmission window

7

foil and air in the test cell. The Appendix contains a chart of the modeling geometry andseveral representative plots of beam propagation at 10 Torr and 150 Torr as well ascontour plots of beam current density as a function of depth into the test cell, seeAppendix A-2. The results of this simulation effort appear in Fig. 8 for a 10-ma electron-beam current incident on the transmission window foil.

IONIZATION RATE AND BEAM CURRENT RADIAL DISTRIBUTION

R(r) =(dE/ds p)(.JW) J(r) = J. exp(-r/ro)

10'a -,- . .... .... , ....... , --...... ...... 10 104.----------------------------------------......

UJ0k. 10-.4A tO.nA-wrg !-1F-

-"1 (25.4,, ) Ad .,,wunwl , mk -,I-

1014 Electron Eiergy A r SS Optical Plane Z 0-- 65-key for P < 10 T•,,,• 0 '•D . . 404,,• it110 Tr .-- . . .

__ _ __ _ ioA o.1 E4

0/ ' 1 0 1 0 10 3 0i t. 1 1 00 0

Ld 10". J• 7 4 "0 |"

Figure 8 Mid pn i o r br tand rad isi.

parspe -, a the rail curn ditibto J1)inAm°apa in Fi.m 8.Th

eeto ch e4mV for P < t0 Ty mDermi to 40-wV at 150 Tor-

-- E- 0.01 V. 10 100 1000 1E-3 0.01 0.1 1 10 100 1000

FRESSURE, Torr PRESSURE, Taff

Figure 8. Mid plane ionization rate, beam current, and radial distribution.

The volumetric ionization rate in Fig. 8 represents the peak ionization rate for a

radial distance r = 0.0 m. The formulas for the radial ionization rate R(r), in electron-ionpairs per m3o s , and the radial current distribution J(r) in anm2 appear in Fig. 8. Thequantity dE/ds is the energy loss in aluminum in jtm2/kg, p is the density of aluminum inkg/m3, (Ep) is the average energy to produce an electron-ion pair in air in J, e is theelectron charge in C, Jo is the maximum current density in /m2 , and re is the 1/e radiusof the current density in m. An exponential radial distribution was deduced from contourplots on the mid plane, such as the ones in the Appendix. The Gaussian electron-beamradial profile incident on the transmission window is transformed into non-Gaussianradial profile, because of electron scattering in the foil. At the mid plane of the test cellthe contour-plot patterns in Appendix A have degraded to an extent that a Gaussian

pattern is no longer present. An exponential profile is used instead.

E. RF Diacinostics.

A microwave absorption and phase measurement system was developed andinstalled in the air-plasma test cell within two large 8-inch CF nipples. The hardware toadapt the horns 'o the nipple is sketched in Fig. 9 and one of the nipples is shown inFigs. 3 and 4. D -tails of the absorption and phase measurement technique are inVidmar eta! (207 6). The system operates at 10 GHz. Direct reflections from the curvedcell wall proved to produce a strong reflection that adds to the direct (one-pass) signal

8

-Nor-Cal Prodoft CF Full Nipple 0-Rag SeelMOWn 2N-600 Zero Cleiatwe

JNrU, A- ' .001 J-R gSeel Flange 0 8 00"Lee Tube ED 0'

MuuV . ~~Fsce-owFace Length. 1100'lPQiiit

142S3Threaede Rod 10 25' Leng~ CFR Mdi00bO-F R FgFre Aoe OIM7 -~ eie v

-p -1- ---- - ---,

... . .......

Figure 9. RF horn mounting fixture detail.

propagating throlugh the test cell.

A 2-ft square panel of laminate absorber was used with a hole cut in the center foreach of the 8-inc i nipple and RF horn assemblies. The magnitude of signal reduction isevident in Fig. 1 C, as measured by a network analyzer operating in the time domain.The primary peak in Fig. 10 is the main signal propagating through the test cell. Thispeak has somne structure that is due to minor reflections of cabling and connectors. Thefirst peak 33.6 dB3 below the direct sign is due to reflection from the curved surface ofthe test cell covered with laminate absorber. The 33.6 dB signal is present in the phasedetector along w'th the direct signal, which limits the phase resolution to approximately1.2 deg.

9

9 Aus 2096 1i055;42

'$12 LOC _0 d REF -22.6 do 2:-45374d 6,34E n

: e.SeA doa,

S'IT-33.6dB

STPT C STOP 40 n

Figure 10. Time domain S 12 of internal reflections at 10 GHz with absorber.

F. Ozone Detection.

The generate n of ozone is a major byproduct of impact ionization of air with anelectron beam. Its concentration and rate of increase provides data on the 0concentration, because the theoretical production rates of 03 depends on the 0concentration. M'easuring ozone is easier than measuring 0 directly. A White cell, asshown in Fig. 11, monitors the light passing through a 25 nm wide band-pass filtercentered on 253.7 nm. This filter is close to the peak of ozone absorption. Figure 12shows the detector and filter hardware details.

180°

Ozone TestGenerator Mercury Light Source

Port

Mirror Qurt

,•;;).; Collimators

Qat "/"" Pressure

QuartzrroM s Gauge

Glass

Ozone TestEvacuationBlower

0.

--.. ------- LIGHT BEAM BATH

Figure 11. White cell mounted in air-plasma test cell for ozone measurement.

10

r" , hroligh Material 31t8 ALIurnunm Sheet

re Patlern

Hamamatsu H5783-03. -. , ".: 03751 22 0mm square, 500mm long

3, Window 10 mm dia, 8 mm effectveMount 4X M2 4 mm deep

3275 • I14 mm square pattern

-- 0 / •I

'350Q13'wkt

i. - -- - -- 1 ' -- Mounted wd one split backup nrig

S=and two O-rings

.• , , , \ 0 35C

cS nMater Ca-

_._..__L li ISplit PTFE Backup Rings. Dash 012, ~0 053 wide, 8i956OK38

PTFE O-Rings, Das 012.

I T. Jcep Andover FW" 254FS25-12 5 0070 wide, 055W417

Bandpass Filter 253 7 nm, 25 nm

Lens 12,5 mn dia 4 mm thikMea&%ed 12 44mm X 3 52 mm

Fici re 12. Hamamatsu H5783-03 fixture and filter housing.

G. Multichannel Sii ultaneous Data Acquisition.

The operation of the air-plasma test cell involves the simultaneous generation ofan electron beam and monitoring sensors to record subsequent information as noted inTable 1. A short triager pulse is used to simultaneously trigger two 4-channel digitalsampling oscilloscopes that monitor the experiment for a few milliseconds. The meshsensor voltage and transmission window signal quantify beam current and via MAGICthe ionization rate on the mid plane. The RF propagation path and optical signal pathscross the plasma on the mid plane of the test cell. The RF signals monitor both powerabsorption and 10 GHz phase from an I-Q detector. The ozone detector monitors lightabsorption and is used to quantify ozone production. In addition to these sensors, aspectrometer mcnitors optical emissions of nitrogen and will eventually provide real-timedata.

Table 1 Multichannel diagnostics.

Ci •inel 1 Trigger Pulse to Electron Gun2 Mesh Voltage to Monitor Beam Current3 Transmission Window Foil4 RF Power Absorption5 RF I-Channel Phase6 RF Q-Channel Phase7 Ozone Signal

11

III RESULTS

The major research results are the following:

* An experimenta! test facility consisting of a 1 00-keV electron gun and a 400-liter air-plasma test cell \v'h microwave, optical, and electronic diagnostics has been developedfor studies of air-plasma generation at pressures from 1 mTorr to 760 Torr.

o Preliminary measurements have been made with all sensors and improvements tothe infrastructure associated with reliable electron source operation are progressing.

12

IV PERSONNEL, INTERACTIONS, AND PUBLICATIONS1 Dec 2003 - 31 May 2007

Personnel. The primary personnel on this project has been

"* Robert J Vidmar, Principal Investigator

"* Kenneth R Stald r, Consultant

Interactions. The research conducted on this project has been presented at the 5 7 th

58th, and 5 9th Gaseous Electronic Conferences, and at the 4 2 nd, 4 3 rd and 4 4 thAerospace Science.; Meeting and Exhibit American Institute of Aeronautics andAstronautics Conference in Reno Nevada, 3 1 st and 3 3 rd International Conference onPlasma Science, anor the 2007 Pulsed Power and Plasma Science Conference. Therewere numerous interactions at these conferences with representatives from DoDLaboratories, Natio ?al Laboratories, private companies, and Universities from aroundthe world.

Publications Supported by AFOSR Grant Number FA9550-1-0015

Vidmar, R. J., and K. R. Stalder, "Electron-Beam Generated Plasma in Air: Pulsed and ContinuousGeneration," Scsý- on 51-WIG-2, AIAA 2004-0359, p 8, 42nd Aerospace Sciences Meeting andExhibit, Reno, NXV' 5-8 Jan, 2004.

Vidmar, R. J., "High-P essure Liquid Cooling for High Repetition-Rate Capacitors," 3 1 st IEEE InternationalConference on Plasma Science, 28 June -1 July, 2004, Baltimore, MD.

Vidmar, R. J., "High R-oetition-Rate Liquid Cooled Capacitors," 3 1st IEEE International Conference onPlasma Scicma, ", 28 June -1 July, 2004, Baltimore, MD.

Stalder, K, Vidmar, I. [ersisyan, G., and W. Graham, "Modeling the Kinetics in High-Pressure GlowDischarges," F'7 2.059, 571h Annual Gaseous Electronics Conference, 26-29 Sept, Shannon, TheRepublic of ItC ýicd, GEC04, 2004, Bulletin of the American Physical Society, 2004.

Vidmar, R. J., and K. R2. Stalder, "Air-Plasma Experimentation at the University of Nevada, Reno,"Session 111-WI 5, AIAA 2005-0791, p 12, 43d Aerospace Sciences Meeting and Exhibit, Reno,NV, 10-13 Jan, )5.

Vidmar, R., K. Stalder aid M. Seeley, "Air-Plasma Test Cell, Electron-Beam Source, and Measurementsof Electron D( ý,:.ity and Ozone Concentration," DM1-6, 581h Annual Gaseous ElectronicsConference, 1;-20 Oct 2005, San Jose, CA, GEC05, 2005, Bulletin of the American PhysicalSociety, Vol 5 JNo 7, p 16, 2005.

Vidmar, R., K. Stalder, -id M. Seeley, "Experimental Details on Air-Plasma Measurements of ElectronDensity and C.- ne Concentration," SW33, 58'h Annual Gaseous Electronics Conference, 16-20Oct 2005, San iose, CA, GEC05, 2005, Bulletin of the American Physical Society, Vol 50, No 7,p 55, 2005.

13

Vidmar, R., K. Stalder. -nd M. Seeley, "Electron Beam Produced Air Plasma: Measurements of ElectronDensity and 0', one Concentration," Session 116-WIG-4, AIAA 2006-0791, p 1 0 , 4 4 th AerospaceSciences Meet sg and Exhibit, Reno, NV, 9-12 Jan, 2006.

Vidmar, R., K. Stalder, ýýnd M. Seeley, "Electron-Beam Produced Air Plasma: Optical Measurements ofBeam Current- Oral Presentation LWl-7, 5 9 th Annual Gaseous Electronics Conference, 10-13Oct 2006, Co!l'iibus, OH, GEC06, 2006, Bulletin of the American Physical Society, Vol 51 ,No 5,p 41, ISSN 00 3-0503(200610)51;5;1-S, 2006.

Vidmar, R., K. Staldor. md M. Seeley, "Electron-Beam Produced Air Plasma: Optical and ElectricalDiagnostics," oster SRP2-13, 591h Annual Gaseous Electronics Conference, 10-13 Oct 2006,Columbus, OF. GEC06, 2006, Bulletin of the American Physical Society, Vol 51 ,No 5, p 41,ISSN 0003-05 2(200610)51 ;5; -S, 2006.

Stalder, K. R., R. J. V ýiiar, G. Nersisyan, and W. G. Graham, "Modeling the Chemical Kinetics of High-Pressure Gio., Discharges in Mixtures of Helium with Real Air," Journal of Applied Physics,Vol 99, No <, , ; 93301-1-8, 1 May 2006.

Vidmar, R.J., K.R. St• cr, and M.V. Seeley, "Electron-Beam Produced Air Plasma: RF and OpticalDiagnostics," ' j IEEE International Conference on Plasma Science, 4-8 June2006, TraverseCity, Michiga: 1 oster 1P35, p 156, IEEE 06CH37759, ISBN 1-4244-0124-0, June 2006.

Vidmar, R.J., K.R. Sic :r, and M.V. Seeley, "Electron-Beam Produced Air Plasma: Optical and ElectricalObservations 23 IEEE International Conference on Plasma Science, 4-8 June 2006, TraverseCity, Michiga! Oral Presentation 3D6, p 219, IEEE 06CH37759, ISBN 1-4244-0124-0, June2006.

Serdyuchenko, A. Y., V. Seeley, Q. J. Sinnott, and R. J. Vidmar, "Application of Tunable Diode LaserSpectroscop'. r Time Resolved Measurements in Electron Beam Produced Plasma," 2007 IEEEPulsed Powe ;-d Plasma Science Conference, 17-22 June 2007,Albuquerque, New Mexico,Poster 2P10, :!ie 2007.

Vidmar, R.J., A. Y. Se vyuchenko, M. V. Seeley, Q. J. Sinnott, and K. R. Stalder, "Electron-BeamGenerated Ai Plasma: Sensors to Quantify Beam Current and Electron Density," 2007 IEEEPulsed Powe- •:,d Plasma Science Conference, 17-22 June 2007,Albuquerque, New Mexico,Poster 2P26, l(;ne 2007.

Serdyuchenko, A. Y., 2 V. Seeley, Q. J. Sinnott, and R. J. Vidmar, "Chemical Composition of ElectronBeam Prod, Air Plasma by Means of Tunable Diode Laser Spectroscopy and NumericalSimulion," 2 7 IEEE Pulsed Power and Plasma Science Conference, 17-22 June2007,A buqii(, je, New Mexico, Oral Presentation 3F1, June 2007.

Vidmar, R.J., A. Y. S <csyuchenko, M. V. Seeley, Q. J. Sinnott, and K. R. Stalder, "Electron-BeamGenerated A• • lasma: Beam Current and Electron Density Distributions," 2007 IEEE PulsedPower and F- • •na Science Conference, 17-22 June 2007,Albuquerque, New Mexico, OralPrese,'atio: 37, June 2007.

14

REFERENCES

Adamovich, I. V., "Control of Electron Recombination Rate and Electron Density inOptically-Puvrned Non-Equilibrium Plasmas," J. Phys D: Appl. Phys., Vol 34, No 3,pp 319-325, 7 Feb, 2001.

Macheret, S. 0., I] N. Shneider, and R. B. Miles, "Modeling of Discharges Generatedby Electron 1eams in Dense Gases: Fountain and Thunderstorm Regimes,"Physics of 'Pasmas, Vol 8, No 5, pp 1518-1528, May, 2001.

Stark, R. H., and K Schoenbach, "Electron Heating in Atmospheric Pressure GlowDischarjes.",. Appl. Phys., Vol. 89, No. 7, pp 3568-3572, 1 April 2001.

Vidmar, R. J., Pla:, ,a Cloaking: Air Chemistry, Broadband Absorption, and PlasmaGenermtion, i', IS, AFOSRTR900544, ADA2220440, p 88, 1990A.

Vidmar, R. J., "On ie Use of Atmospheric Pressure Plasmas as ElectromagneticReflectors anr! Absorbers," IEEE Transactions on Plasma Science, Vol 18, No 4,pp 733-741, 4iig, 1990B.

Vidmar, R., K. Staldr r, and M. Seeley, "Electron Beam Produced Air Plasma:Measuremen s of Electron Density and Ozone Concentration," Session 116-WIG-4, AIAf,, 2006-0791, p 10, 4 4 th Aerospace Sciences Meeting and Exhibit,Reno, NV, I12 Jan, 2006.

Yu, L, C. 0. Laux, M Packan, and C. H. Kruger, "Direct-Current Glow Discharges inAtmospheric ressure Air Plasma," J. Appl. Phys., Vol. 91, No. 5, pp 2678-2686, 1March 2002.

15

APPENDIX

MAGIC TEST CELL GEOMETRY A-2MAGIC DIAGNOS C DATA A-3

FIGURES

Figure Al. Geometry of air-plasma test cell used for MAGIC modeling. A-2Figure A2. Propa ;iation in 10 Torr air. A-3Figure A3. Prop: I,-tion in 150 Torr air. A-3Figure A4. Electr-,. beam current density incident on transmission-window foil. A-4Figure A5. Electron beam current density on plane z = 10.51 cm. A-4Figure A6. Electro•; beam current density on mid plane z = 30.56 cm. A-5Figure A7. Electr) r,-beam energy versus distance at 10 Torr. A-6Figure A8. Electr- -beam current versus distance at 10 Torr. A-6

A-1

MAGIC TEST CELL GEOMETRY

The air-plasr.-na test cell and electron beam transmission window were modeled inCartesian coordinales. The side view in Fig. Al is a two dimensional, y-z plot for x = 0cm. The electron Leam enters a vacuum section 6 cm in diameter at z = 0 cm. ATeflon insulator supports an aluminum clamping ring connected to ground via a loadresistor. The tran ýiission window is at z = 5 cm. The mid plane is half way into thetank and has z= 5 cm (12 inch).

Geometx(y,ox@ 5.000 mm)

N

0• ,I I , ,

-400 -200 0 200 100 600

ym)

Surf ace ,t1 =4 p '100 mm) ... .Auh: R VidmarBeam Pr pa," :,r Air: P = 5 00E+00 Torr, Foil = 1.O0E+00 mils Orgn: University of Nevada, Reno[,uration = 1 OCS-_, ris, Number of Particles - 50 Devc: Air-Plasma Test CellElectron c - 100 kV, I = 1.OOE-02 A, J - 3.12E+00 A/m2 File: UNR Air Plasma 003 foil window grap. f : .... .. OD 2007, ,,D.o ' ::,r§N 1$'98-2Q'0., AT. riýM -. oln Syst..ea Jun 12,2007 16:02:29 Page: 1

Figure Al Geometry of air-plasma test cell used for MAGIC modeling.

A-2

MAGIC DIAGNOSTIC DATA

9.999ns: foiallparticles

100 200 300 400 500 600

z(mm)

Auth: R VicimarBeam F'r pqI, in Air: P - 1.OOE.0l Torr, Foil - I OOE-.00 mils Orgn: Univesfty of Nevada, RenmDUt M1:1- z.0, 1 ns, Number of Parlicles - 50 Devc: Air-Plasma Test CallEiectrcn'ur 100kVI 1 .00E-02 A, J = 3.12E+00 AA112 File: UNR Air Plasma 003 foil window grap

0620+7 A 19'3-2007 iw A7U-' "1n2.2007 14:.51:28 Page: 260

Figure A2. Propagation in 10 Torr air.

9.999 ns: fbi all particles

100 200 300 400 500 600

z(lam)

Auth: R VidmarE FrPcpq- Fin Air:P=1.50E.02 Torr Fodi 0(.OE00 eis Orgri: Uiniversity of Nevada, Reno

Ct it tirn I i 01 ns, Number of Particles - 50 Deyc: Air-Plasma Test CeallEý ttSo V = 100 kV ,I = 1 .OOE-02 A, J - 3.12E.00 A/m2 Fie: LINRU Air Plasma 003 foil window grap

t~>r1~0207r F~ i nrA kn 14'2007 08:35:38 Page: 26

Figure A3. Propagation in 150 Torr air.

A-3

9.999 ns: Jz (Alm* *2) at PARALLELT PLANE_1

0.80

20 E-E l 0.00IL~ 0-040

0- M*0.80

-20 1

* 2.00

-40 *24

NONE2 80

-1U -50 0 so00a

PlaneatX3=- 1 43.' Auth: R VidmarBeam Propagiticr ir rn P = 1 OOE+01 Torr, Foil= I .00E+0 MRS Orgn: University of Nevada, RenoDuralion = -1 00E+0I -, Number of Particles = 50 Devc: Air-Plasma Test CellElect, n So, it c Vý i kVI=1-1OOE-02 AJ-=3.12E+00 Afm2 File: UNR Air Plasma 003 foil window grap

MA O00' Cý: zt2,T~Lsa effl Jun 12,2007 14:51:26 Page: 263

Figure A4. El, (Aron beam current density incident on transmission-window foil.

9,999 ns: Jz (Aim**2) at PARALLELPLANE_2

100

500

-110.11

0-0.60

-10 0 00 00 03

-50 muPlaneat XI; i Auth R-V0.3a

Bea Prl:'. -ti P1 .OE+1 Trr oil= .OE+0 mis Ogn:Unverityof evaa,4en

Dut0 W1 M-0.5mbr3 arils=50Dv:Ai-lsa etCl

Euectron => Ie : / I kV+ I [Ime 1f .OOEtJ2 A, = 351 2E0 D2Fec:UN Air-Plasma 003t follwnowga

AMý&-OO ýD1 07'; -ye ~ ~ Jn120 52 Page: 265

Fiur 5. Electron beam current density on plane z =10.51 cm.

A-4

9.999 ns: Jz (A/m**2) at PARALLELPLANE_4

X 2)

201J

-200 . .00

-200 0 200 400

Surface at _iý=:34 1' 30 er) Auth: R VidmarBearri Propa•_iatior in P = 1.OOE+01 Torr, Foil = 1.OOE+00 mils . Orgn: Universiy of Nevada, RenoDuration = I _IE+i1 Jurmber of Particles = 50 Devc: Air-Plasma Test CellElectron Sc uce = A I = 1.OOE-02 A, J - 3.12E+00 AMn2 File: UNR Air Plasma 003 foil win-dow grap

8&2k? Žý4 TX Msv Syzztefr- Junl12,2007 14:51:26 Page:267

Figure A( Electron beam current density on mid plane z = 30.56 cm.

A-5

9999 ns: PARTICLE ElETRON Positive EnergyfluxJparticle

100

s0

60 -6i0

20 -

20

0100 0 300 400 500 600

Au.. •thR VidarEi,'riP: .1Pc in Air: P = 1.O0E+01 Torr, Foil= 1.00E+00 mils Orgn: University of Nevada, RenoD,,it.-,tion = I CI ns, Number of Particles - 50 Devc: Air-Plasma Test CellEltron S:u- u = 100 kV, I = 1.OOE-02 A. J = 3 12E+00 Afn2 Fie: UNfL Ar Plasma 003 foil window grap

..... 2 . , 1:C.-2O@7C•O A yMeS• .... 12,2007 14:51:26 Page: 277

Figur, A7. Electron-beam energy versus distance at 10 Torr.

9.999 ns: PARTICLE ELECTRON Positive Current

U

-4

C.)

-6

-10 -

I I I I I

100 200 300 400 500 600

Aýut R ViCdarBe.,rn Pro:,i Ii,::: in Air: P = 1.OOE+01 Torr, Foil = 1.OOE+00 mils Or.. . Un.rve'rs-/y of Nevada, Reno[:,ur n1tion I i I I 1 ns, Number of Particles - 50 Devc: Air-Plasma Test CellE;tin t, ". 100 kV, I = 1 E-02 A, J = 3.1 2E÷00 An2 Fie: UNR Air Plasma 003 foil window grap

2 A TK. o £y~reer .sA 12,2007 14:51:26 Page: 278

Figure A8. Electron-beam current versus distance at 10 Torr.

A-6