ROA-RIB5 683 MODULATION OF AN INTENSE BERM BY AN EXTERNAL MICROWAVE 1I/0y SOURCE - THEORY AND SIMULATION(U) NAYAL RESEARCH LABI HASHINGTON DC J KRALL ET AL. B? OCT B? NRL-MR-6SB3

UNCLSSIFED D-RI9-86E1358 F/O26/B

MoEKE..

U.5!

= "a11I1 A 110 .

MICROCOPY RESOLUTION TEST CHART6,-__Ua.W_ L.UeEA OF. STANDARD- 196-A,

* U U 0 Al6 .6 0 0 0 0 0 0 0

K.N

• • • , .. .• • • ) 4 • •

NRL Memorandum Report 6083

* 00

* I,)00

Modulation of an Intense Beam by an ExternalMicrowave Source - Theory and Simulation

J. KRALL* AND Y. Y. LAU

Plasma Theory BranchPlasma Physics Division

*Science Applications Intl. Corp.

October 7, 1987

DTICS ELECT-

NOV 0 5 1987 D

Approved for public release; distribution unlimited.

67 i" i4 370

SECURITY CLASSIFICATION OF THIS PAGE Aei / -0

Ia. REPORT SECURITY CLASSIFICATION 1b. RESTRICTIVE MARKINGSUNCLASSIFED

2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBUTION /AVAILABILITY OF REPORT

2b DECLASSIFICATION / DOWNGRADING SCHEDULE Approved for public release; distribution unlimited.

4. PERFORMING ORGANIZATION REPORT NUMBER(S) S. MONITORING ORGANIZATION REPORT NUMBER(S)

6a. NAME OF PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION(if applicable)

Naval Research Laboratory Code 4790

6c. ADDRESS (City, State, and ZIP Code) 7b ADDRESS (City, State, and ZIP Code)

Washington, DC 20375-5000

Ba. NAME OF FUNDING/SPONSORING ib. OFFICE SYMBOL 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBERORGANIZATION (If applicable)

U.S. Department of Energy8c. ADDRESS (City, State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERS

PROGRAM PROJECT TASK WORK UNIT

Washington, DC 20545 ELEMENT NO N 1 Al05.86 NO CCESSION NODOE ER13585

11. TITLE (include Security Classification)Modulation of an Intense Beam by an External Microwave Source-Theory and Simulation

12 PERSONAL AUTHOR(S)Krall* J. and Lau, Y.Y.

13a TYPE OF REPORT 13b TIME COVERED 14, DATE OF REPORT (Year, Month, Day) IS PAGE COUNTInterim FROM TO 1987 October 7 18

16 SUPPLEMENTARY NOTATION

*Science Applications Intl. Corp.

17 COSATI CODES 18 SUBJECT TERMS (Continue on reverse if necessary and Identify by block number)

FIELD GROUP SUB-GROUP .*Current modulation , Intense relativistic electron beam

, I Highpower T amplifier

19 ABSTRACT (Continue on reverse if necessary and identiy by block number)

A time dependent, fully electromagnetic particle code is used to simulate the current modulation in an intense rela-tivistic electron beam (IREB) by an external rf source. It is shown that the intense beam may serve as a power amplifierwith good phase stability, as suggested in earlier experiments. Increase in beam bunching by the DC space charge isdemonstrated with a simple analytical model. / ,

20 DISTRIBUTION./AVAILABILITY OF ABSTRACT J21 ABSTRACT SECURITY CLASSIFICATIONX UNCLASSIFIEDIUNLIMITED 0 SAME AS RPT Q OTIC USERS UNCLASSIFIED

22a NAME OF RESPONSIBLE INDIVIDUAL 22b TELEPHONE (Include Area Code) 22c OFFICE SYMBOL

Y.Y. Lau (202) 767-2765 Code 4790DO Form 1473. JUN 86 Previous editions are obsolete SECURITY CLASSIFICATION OF THIS PAGE

U % tttt,:ab..XL'*'r.C SC- .Y tt * '- ; tA Ce,% t .;. .. .

. ..'

., . . ,, .

Modulation of an Intense Beam by an ExternalMicrowave Source-Theory and Simulation

The experimental demonstration of deep current modulation in an

intense relativistic electron beam (- 5 kA, 500 keV) by a moderate external

rf source (- 50 kW) suggests strong potentials2'3 to amplify rf power to

gigawatts at frequencies between 1 GHz to 10 GHz. Several unusual

properties were discovered in the experiments 1 4 , namely, the high degree

of phase and amplitude stability in the output signal1 , the ease with which

the current modulation can be achieved and may be manipulated by the

introduction of additional, undriven cavities downstream, and the possible

avoidance of electrical breakdown at the gaps even at a high level of beam

modulation5 . These unexpected features are only partially understood. The

major obstacle to a complete understanding is the highly nonlinear

interaction in complex geometries involving the kinetic energy, rf energy,

and the potential energy of the beam, all of which are of the same order of

magnitude. The crucial role played by the potential energy, which

necessarily accompanies an intense beam, renders the classical picture of

beam bunching invalid.

We, therefore, resort to a time dependent, two-dimensional, fully

electromagnetic particle code, CONDOR6 , to simulate the response of an

intense beam to an external rf excitation. This amplifier configuration

has never been subject to particle simulation, although self-excited

7oscillations have been studied in the past . We found that when the

external rf drive is low, the induced rf current agrees well with the small

1,7signal theory . Addition of a second cavity in the drift region

significantly enhances the current modulation, without loss of phase

stability, as observed in earlier experiments 1. An analytical model is

presented to show that the DC space charges associated with the intense

beam may encourage current bunching as the beam traverses a modulating gap.

Manuscript approved Jy 24, 1987.

The harmonic content is assessed. The details, together with experimental

4observations, will be published elsewhere

To mimic the experiments as closely as possible, the simulation

geometry [Fig. 11 consists of a 500 keV, annular IREB with beam radius

rb - 1.9 cm and beam current I° = 5 kA propagating along a metal cylinder

of radius r = 2.4 cm. A static 10 kG axial magnetic field confines the

IREB. A gap feeding a coaxial cavity 5.6 cm long is inserted into the

drift tube. An infinite radial transmission line (not shown) is attached

to the outer wall of this cavity and "pumps" rf energy into the cavity at a

frequency f = 1.37 GHz, the resonsance frequency of the cavity. At t = 0,

the rf drive is turned on. At t = 6 ns, after the fundamental mode of the

cavity has saturated, the beam current is ramped up, reaching its full

value at t = 11 ns (5 ns rise). The simulation continues until t = 20 ns.

For rf drives yielding gap voltages with amplitude V 1 = 30 kV and

V1 = 6 kV, the axial distribution of the normalized rf current 11 Cz)/I ° in

steady state is shown in Fig. 2. The temporal evolution of the beam

current at a distance z = 28 cm from the gap center is shown in Fig. 3a for

the V1 = 30 keV case.

The above results may be compared with linear theory7 ,l: An rf

voltage VIsinwt at the gap would induce an rf current 11(z)cos(W(t-z/v0 ))

at a position z downstream, where

11 (z) = I V sin z (1)

Here, v is the average electron speed in the drift region 8 , V = (eV1/MC

2

/(y 0o2o/ 0 = 2n(z/X)a 1/2/3o2YO , 6 = 2 2 - ),c = Io/IsYo3 0 ,

I s = 8.53 kA/ln(rw/rb), X=2nc/w, 0=vo/c, yo=(y0o1) - 0 The axial

dependence 11(z)/l 0 according to expression (1) is shown by the dashed

curves in Fig. 2, using the same parameters as in the simulation: I =

5kA, X = 21.9 cm, Is = 36.5 kA, Yo 1.67. Note that Eq. (1) and Fig. 2

2

J. '. -. . .o " r r r -

imply linear dependence of 11 on V1 when V1 is small. As V1 increases, the

current modulation would contain harmonic components In (z) a 2 IoJ n

(n Vsinz) where Jn is the Bessel function of order n. This estimate shows

that only the fundamental component (n=l) is significant if 7 < 0.3.

To obtain a current modulation comparable to 10, V1 should also be of

the same order of the beam voltage. It is impractical to excite such a

large gap voltage directly from an external rf source. Instead, one may

insert a second cavity downstream [Fig. Ib], at a location where the

current modulation (by the first cavity) reaches a maximum1 . This second

cavity is identical to the first, but is not externally driven. Using the

same rf drive as that for Fig. 3a, we show in Fig. 3b the temporal

evolution of the beam current at 6 cm downstream from the second gap, at

which the gap voltage is 330 keV. The total current modulation thire

increases to 57%, including all harmonics. In fact, the modulation level

continues to increase over the remaining 10 cm of propagation distance,

reaching 85%. No particle reflections were observed at the second gap, nor

transients were important. These results compare favorably to both the

experimental two-cavity result, in which the cavity separation was 5 cm and

modulation greater than 80% was observed at 1.328 GHz1 , and to more recent4

results in which the separation is 32 cm4. In this situation, the harmonic

content is considerable, with as many as eleven harmonics clearly

observable in the current measured immediately downstream from the second

gap.

Substantial current modulation immediately beyond a gap is a property

of an intense beam which cannot be expected from the conventional klystron

theory. While the details are not fully understood, the following scenario5

emerges : When the beam current 10 approaches the limiting value, IL? the

3

"- • , , .'? "':%

DC potential energy is nontrivial, especially near the gap. If the

modulating voltage V1 at the gap is sufficiently large, the instantaneous

beam current may exceed the limiting value during the part of the rf cycle

when the rf voltage is in the same phase as the retarding voltage caused by

the DC self field of the beam. This then leads to strong current

modulation once the beam exits the gap. In a simple model, the current

modulation 11/10 at the gap exit reads:

ti1 0) e m (i - Vth /Vl (2)

where the threshold voltage Vth is given by

Vth = 0c2 l - 2/1 (inj 2/3 _ ')1 2} (3

in terms of the injection y and the limiting current IL . This current

modulation is absent if V1 < Vth, but rises rapidly once V1 > Vth, and

becomes insensitive to V1 if the latter substantially exceeds Vth [c.f. Eq.

(2)]. These features are also reflected qualitatively in experiments.

Finally, by varying the phase of the external rf drive in the two-

cavity geometry [Fig. ib], we have found that the current modulation signal

is phase-locked to the external drive to within an error of 1.1 ± .6%, in

agreement with the experimental observation1 .

In summary, several unusual features observed in experiments on the

modulation of an intense beam are confirmed in the particle simulation.Useful analytic models are constructed.

We are grateful to M. Friedman and V. Serlin for many stimulating

discussions, and for their support. We are also indebted to Scott Brandonand to Adam Drobot for their assistance in applying CONDOR6 to this

problem. This work is supported by the Department of Energy, Contract No.

DE-AI05-86 ER 13585.

4

References

1. M. Friedman and V. Serlin, Phys. Rev. Lett. 55, 2860 (1985).

2. M. Friedman and V. Serlin, Appl. Phys. Lett. 49, 596 (1986).

3. M. Friedman, V. Serlin, A. Drobot and A. Mondelli, IEEE Trans., Plasma

Sci., PS-14, 201 (1986).

4. M. Friedman, V. Serlin, J. Krall and Y. Y. Lau, submitted to Phys.

Fluids.

5. M. Friedman and V. Serlin, private communication.

6. CONDOR is an extension of the MASK particle code, discussed in A.

Palevsky and A. Drobot, "Application of E-M P.I.C. codes to microwave

devices," in Proc. 9th Conf. Numerical Simulation of Plasmas

(Northwestern Univ., Evanston, IL), July 1980 (unpublished).

7. M. Friedman, V. Serlin, A. Drobot and L. Seftor, Phys. Rev. Lett. 50,

1922 (1983); Also J. Appl. Phys. 56, 2459 (1984).

8. Since the electrons already spend some energy to set up the space

charge depression in the drift region, their drift speed u° is

somewhat less than the value at injection.

Accession For

NTIS GRA&IDTIC TABUnannounced 0Justification

/ By

Distribution/

Availability Codes'Xv::[1 and/or

As NSPEcTED

L6

5

~rf DRIVE

6-

"9° 4L. (a)

2

0i

0 10 20 30/ 40 50

INTENSE E-BEAM

frf DRIVE

6 .

(b)2

0 10 20 30 40 50

CENTER AXIS (cm)Fig. 1 (a) The geometry. Current modulation is provided by the

externally driven cavity at left.

(b) A second cavity is inserted to enhance current modulation.

6 ,

0.15- 1 V1 =30kW

0.10-

SIMULATION

ANALYTICAL

0.05-

V1 =6kW

o0 10 20 30 40 50z (CM)

Fig. 2 Fraction of the modulated current for Fig. la, at two

levels of the rf drive.

7

N,.~ . .

0.0

1.5-

3.0- -(a)

4.5-

6.00 4 8 12 16 20

t (ns)

0

3

II (b)" 6"

9

12 * - -

0 4 8 12 16 20t (ns)

Fig. 3 (a) Current response measured at z = 28 cm from the gap for

Fig. la, with gap voltage V1 = 30 kV.

(b) Current response measured at 6 cm downstream of the second

(right) cavity in Fig. lb, with V1 = 30 kV at the first

cavity.

8

DISTRIBUTION LIST*

Naval Research Laboratory4555 Overlook Avenue, S.W.Washington, DC 20375-5000

Attn: Code 1000 - Commanding Officer, CAPT William C. Miller1001 - Dr. T. Coffey1005 - Head, Office of Management & Admin.1220 - Mr. M. Ferguson2000 - Director of Technical Services2604 - NRL Historian2628 - Documents (22 copies)2634 - D. Vilbanks4000 - Dr. V. R. Ellis4600 - Dr. D. Nagel4603 - Dr. W.W. Zachary4700 - Dr. S. Ossakow (26 copies)4700.1 - Dr. M. Friedman (10 copies)4700.1 - V. Serlin (5 copies)4710 - Dr. J.A. Pasour4710 - Dr. C.A. Kapetanakos4730 Dr. R. Elton4730 - Dr. B. Ripin4740 - Dr. W.M. Manheimer4740 - Dr. S. Gold4790 - Dr. P. Sprangle4790 - Dr. C.M. Tang4790 - Dr. M. Lampe4790 - Dr. Y.Y. Lau (50 copies)4790 - Dr. G. Joyce4790 - Dr. T. Godlove4790A- V. Brizzi6840 - Dr. S.Y. Ahn6840 - Dr. A. Ganguly6840 - Dr. R.K. Parker6843 - Dr. N.R. Vanderplaats6875 - Dr. R. Wagner

* Every name listed on distribution gets one copy except for

those where extra copies are noted.

9

Prof. I. Alexeff Prof. A. BersDept. of Electrical Engineering Dept. of Electrical EngineeringUniversity of Tennessee MITKnoxville, TN 37996-2100 Cambridge, MA 02139

Dr. Bruce Anderson Prof. Charles K. BirdsallLawrence Livermore National Laboratory Dept. of Electrical EngineeringL-436 University of CaliforniaP. 0. Box 808 Berkeley, CA 94720Livermore, CA 94550

Dr. H. Brandt

Dr. T. Antonsen Department of the ArmyUniversity of Maryland Harry Diamond LaboratoryCollege Park, MD 20742 2800 Powder Mill Rd.

Adelphi, MD 20783Assistant Secretary of theAir Force (RD&L) Dr. Charles BrauRoom 4E856, The Pentagon Los Alamos National ScientificWashington, D.C. 20330 Laboratory

P.O. Box 1663, M.S. - 817Dr. W. A. Barletta Los Alamos, NM 87545Lawrence Livermore National Lab.P. 0. Box 808 Dr. R. BriggsLivermore, CA 94550 Lawrence Livermore National Lab.

Attn: (L-71)Dr. L. R. Barnett P.O. Box 8083053 Merrill Eng. Bldg. Livermore, CA 94550University of UtahSalt Lake City UT 84112 Prof. 0. Buneman

ERL, Stanford UniversityDr. Robert Behringer Stanford, CA 94305Office of Naval Research1030 E. Green Dr. K. J. ButtonPasadena, CA 91106 Francis Bitter Natl. Magnet Lab.

Mass. Institute of TechnologyDr. G. Bekefi Cambridge, MA 02139Mass. Institute of Tech.Bldg. 26 Dr. J. A. ByersCambridge, MA 02139 Lawrence Livermore National Lab.

Attn: (L-630)Prof. Herbert Berk P. 0. Box 808Institute for Fusion Studies Livermore, CA 94550University of TexasAustin, TX 78712 Prof. J. D. Callen

Nuclear Engineering Dept.Dr. T. Berlincourt University of WisconsinOffice of Naval Research Madison, Ui 53706Attn: Code 420Arlington, VA 22217 Dr. Malcolm Caplan

4219 Garland DriveDr. I. B. Bernstein Fremont, CA 94536Mason LaboratoryYale University400 Temple StreetNew Haven, CT 06520

10

a .. . .- a. - . - . -

Dr. Maria Caponi Dr. R. DavidsonTRW, Building R-1, Room 1184 Plasma Fusion CenterOne Space Park Mass. Institute of Tech.Redondo Beach, CA 90278 Cambridge, MA 02139

Prof. Frank Chan Dr. John DawsonSchool of Eng. & Applied Sciences Physics DepartmentUniv. of Calif. at Los Angeles University of California7731 K Boelter Hall Los Angeles, CA 90024Los Angeles, CA 90024

Dr. David A. G. DeaconDr. V. S. Chan Deacon ResearchGA Technologies Suite 203P.O. Box 85608 900 Welch RoadSan Diego, CA 92138 Palo Alto, CA 94306

Dr. D. P. Chernin Defense Tech. Information Ctr. (2 copies)Science Applications Intl. Corp. Cameron Station1720 Goodridge Drive 5010 Duke StreetMcLean, VA 22102 Alexandria, VA 22314

Prof. M. V. Chodorov Deputy Under Secretary ofGinzton Laboratory Defense for R&ATStanford, University Room 3E114, The PentagonStanford, CA 94305 Washington, D.C. 20301

Dr. William Colson Dr. W. W. DestlerBerkeley Research Asso. Dept. of Electrical EngineeringP. 0. Box 241 University of MarylandBerkeley, CA 94701 College Park, MD 20742

Dr. William Condell Prof. P. DiamentOffice of Naval Research Dept. of Electrical EngineeringAttn: Code 421 Columbia University800 N. Quincy St. New York, NY 10027Arlington, VA 22217

Director of Research (2 copies)Dr. Richard Cooper U. S. Naval AcademyLos Alamos National Scientific Annapolis, MD 21402LaboratoryP.O. Box 1663 Dr. Gunter DohlerLos Alamos, NM 87545 Northrop Corporation

Defense Systems DivisionProf. B. Coppi 600 Hicks RoadDept. of Physics, 26-217 Rolling Meadows, IL 60008MITCambridge, MA 02139 Dr. Franklin Dolezal

Hughes Research LaboratoryDr. Bruce Danly 3011 Malibu Canyon Rd.MIT Malibu, CA 90265NV16-174Cambridge, MA 02139 Dr. A. Drobot

Science Applications Intl. Corp.1710 Goodridge RoadMcLean, VA 22102

IF 11

Dr. Dwight Duston Dr. C. GrabbeStrategic Defense Initiative Org. Department of PhysicsOSD/SDIO/IST University of IowaWashington, DC 20301-7100 Iowa City, Iowa 52242

Dr. Luis R. Elias Dr. V. L. GranatsteinQuantum Institute Dept. of Electrical EngineeringUniversity of California University of MarylandSanta Barbara, CA 93106 College Park, MD 20742

Dr. W. Fawley Dr. R. HarveyL-626 Hughes Research LaboratoryLawrence Livermore National Laboratory 3011 Malibu Canyon RoadP. 0. Box 808 Malibu, CA 90265Livermore, CA 94550

Prof. Herman A. HausDr. F. S. Felber Mass. Institute of Technology11011 Torrynana Road Rm. 36-351San Diego, CA 92121 Cambridge, MA 02139

Dr. H. Fleischmann Dr. Fred HopfCornell University Optical Sciences Building, Room 602Ithaca, NY 14850 University of Arizona

Tucson, AZ 85721Dr. Lazar FriedlandDept. of Eng. & Appl. Science Dr. G. L. JohnstonYale University NW 16-232New Haven, CT 06520 Mass. Institute of Tech.

Cambridge, MA 02139Dr. R. Gajewski (5 copies)Div. of Advanced Energy Projects Dr. Shayne JohnstonU. S. Dept of Energy Physics DepartmentWashington, DC 20545 Jackson State University

Jackson, MS 39217Dr. Richard L. GarvinIBM, T. J. Watson Research Ctr. Dr. Howard JoryP.O. Box 218 Varian Associates, Bldg. 1Yorktown Heights, NY 10598 611 Hansen Way

Palo Alto, CA 94303Prof. Ward GettyUniversity of Michigan Prof. Terry KammashAnn Arbor, MI 48109 University of Michigan

Ann Arbor, MI 53706Prof. Ronald Gilgenbach (3 copies)Dept. Nucl. Engineering Prof. Donald KerstUniversity of Michigan 3291 Chamberlin HallAnn Arbor, MI 48109 University of Wisconsin

Madison, WI 53706

Dr. B. B. GodfreyMission Research Corporation Dr. K. J. Kim, MS-1011720 Randolph S.E. Lawrence Berkeley Lab.Albuquerque, NM 87106 Rm. 223, B-80

Berkeley, CA 94720

12

Dr. A. Kolb Dr. John McAdooMaxwell Laboratories, Inc. Dept. of Electrical Engineering8835 Balboa Avenue University of MarylandSan Diego, CA 92123 Relocatable Classroom, Bldg. 335

College Park, MD 20742Dr. J. Krall (20 copies)Science Applications Intl. Corp. Prof. George Morales1710 Goodridge Drive Dept. of PhysicsMcLean, VA 22102 U.C.L.A.

Los Angeles, CA 90024Prof. N. M. KrollDepartment of Physics Dr. Philip MortonB-019, UCSD Stanford Linear Accelerator CenterLa Jolla, CA 92093 P.O. Box 4349

Stanford, CA 94305Dr. S. P. KuoPolytechnic Institute of NY Dr. J. NationRoute 110 Cornell UniversityFarmingdale, NY 11735 Ithaca, NY 14850

Dr. Thomas Kvan Dr. Kelvin NeilLos Alamos National Scientific Lawrence Livermore National Lab.Laboratory, MS608 Code L-321, P.O. Box 808P. 0. Box 1663 Livermore, CA 94550Los Alamos, NM 87545

Dr. T. OrzechovskiDr. Willis Lamb L-436Optical Sciences Center Lawrence Livermore National Lab.University of Arizona P. 0. Box 808Tucson, AZ 87521 Livermore, CA 94550

Dr. Rulon K. Linford Prof. E. OttCTR-11, Mail Stop: 646 Department of PhysicsLos Alamos National Laboratory University of MarylandP. 0. Box 1663 College Park, MD 20742Los Alamos, NM 87545

Dr. Robert B. PalmerDr. John Madey Brookhaven National LaboratoriesS.P.R.C. Associated Universities, Inc.Physics Department Upton, L.I., NY 11973Stanford UniversityStanford, CA 94305 Dr. Richard H. Pantell

Stanford UniversityDr. J. Mark Stanford, CA 94305Lawrence Livermore National Lab.Attn: L-477 Dr. Dennis PapadopoulosP. 0. Box 808 Astronomy DepartmentLivermore, CA 94550 University of Maryland

College Park, Md. 20742Dr. W. E. MartinL-436 Dr. R. R. ParkerLawrence Livermore National Lab. NW16-288P. 0. Box 808 Plasma Fusion CenterLivermore, CA 94550 MIT

Cambridge, MA 02139

13

- "b. AA MA FWW A %-

Dr. C. K. N. Patel Dr. J. ScharerBell Laboratories ECE Dept.Murray Hill, NJ 07974 Univ. of Wisconsin

Madison, HI 53706Dr. Richard M. PatrickAVCO Everett Research Lab., Inc. Dr. E. T. Scharlesmann2385 Revere Beach Parkway L626Everett, MA 02149 Lawrence Livermore National Laboratory

P. 0. Box 808Dr. Claudio Pellegrini Livermore, CA 94550Brookhaven National LaboratoryAssociated Universities, Inc. Dr. Michael SchlesingerUpton, L.I., NY 11973 ONR Code 1112

800 N. Quincy StreetDr. Sam Penner Arlington, VA 22217-5000National Bureau of Standards,RADP B102 Prof. S. P. SchlesingerWashington, DC 20234 Dept. of Electrical Engineering

Columbia UniversityDr. Hersch Pilloff New York, NY 10027Code 421Office of Naval Research Dr. Howard SchlossbergArlington, VA 22217 AFOSR

Bolling AFBDr. Donald Prosnitz Washington, D.C. 20332Lawrence Livermore National Lab.Attn: L-470 Dr. George SchmidtP. 0. Box 808 Stevens Institute of TechnologyLivermore, CA 94550 Physics Department

Hoboken, NJ 07030Dr. M. ReiserUniversity of Maryland Dr. H. SchwettmannDepartment of Physics Phys. Dept. & High EnergyCollege Park, MD 20742 Physics Laboratory

Stanford UniversityDr. S. Ride Stanford, CA 94305Johnson Space CenterHouston, TX 77058 Dr. Marlan 0. Scully

Dept. of Physics & AstronomyDr. C. W. Roberson (5 copies) Univ. of New MexicoCode 412 800 Yale Blvd. NEOffice of Naval Research Albuquerque, NM 87131800 N. Quincy StreetArlington, VA 22217 Dr. A. M. Sessler

Lawrence Berkeley LaboratroyDr. Marshall N. Rosenbluth University of CaliforniaInstitute for Fusion Studies 1 Cyclotron RoadThe Univ. of Texas at Austin Berkeley, CA 94720Austin, TX 78712

Dr. W. SharpDr. N. Rostoker L-626University of California Lawrence Livermore National LaboratoryDepartment of Physics P. 0. Box 808Irvine, CA 92717 Livermore, CA 94550

14

Dr. R. Shefer Dr. Keith Thomassen, L-637Science Research Laboratory Lawrence Livermore National Laboratory15 Ward Street P. 0. Box 808Somerville, MA 02143 Livermore, CA 94550

Dr. Shen Shey (2 copies) Dr. K. TsangDARPA/DEO Science Applications Intl. Corp.1400 Wilson Boulevard P.O. Box 2351Arlington, VA 22209 La Jolla, CA 92038

Dr. D. J. Sigmar Dr. H. S. UhmOak Ridge National Laboratory Naval Surface Weapons CenterP. 0. Box Y White Oak Lab.Oak Ridge, TN 37830 Silver Spring, MD 20903

Dr. J. S. Silverstein Under Secretary of Defense (R&E)Harry Diamond Laboratories Office of the Secretary of Defense2800 Powder Mill Road. Room 3E1006, The PentagonAdelphi, MD 20783 Washington, D.C. 20301

Dr. Jack Slater Dr. L. VahalaSpectra Technology Physics Dept.2755 Northup Way College of William & MaryBellevue, VA 98004 Williamsburg, VA 23185

Dr. Lloyd Smith Ms. Bettie WilcoxLawrence Berkeley Laboratory Lawrence Livermore National Lab.University of California ATTN: Tech. Info. Dept. L-31 Cyclotron Road P.O. Box 808Berkeley, CA 94720 Livermore, CA 94550

Dr. R. Sudan Dr. J. VurteleCornell University M.I.T.Ithaca, NY 14850 NW 16-234

Plasma Fusion CenterDr. David F. Sutter Cambridge, MA 02139ER 224, GTNDepartment of Energy Dr. A. YarivWashington, D.C. 20545 California Institute of Tech.

Pasadena, CA 91125Dr. T. TajimaIFSUniv. of TexasAustin, TX 78712

Dr. Milan TekulaAVCO Everett Research Lab.2385 Revere Beach ParkwayEverett, MA 02149

Dr. R. TemkinMass. Institute of TechnologyPlasma Fusion CenterCambridge, MA 02139

15

115

Moab