Exploding Wires: Volume 2 Proceedings of the Second Conference on the Exploding Wire Phenomenon, Held at Boston, November 13–15, 1961, under the Sponsorship of the Geophysics Research Directorate, Air Force Cambridge Research Laboratories, Office of Aeros

317 Pages·1995·11.84 MB·English

by  William G. Chace (auth.)

EXPLODING WIRES
Single-fringe, streak interferogram taken in white light and showing the
explosion at 20 kv of a 4-mil copper wire in argon at ~ atm. The outermost
boundary is the head shock trajectory while the rounded tip represents the
peripheral arc. Behind the shock wave fringeshift is positive. The locus of
zero shift passes through the shock just .outside the peripheral arc. Within
the arc fringeshift is negative, indicating the presence of electrons. The
complex, jagged fringes near the axis attest to a high degree of cylindrical
symmetry in the expanding metal. This picture corresponds to Fig. 6d of
the paper by F. D. Bennett and D. D. Shear, where further discussion may
be found.
EXPLODING WIRES
VOLUME 2
Proceedings of the Second Conference on the Exploding Wire
Phenomenon, Held at Boston, November 13-15, 1961, under
the Sponsorship of the Geophysics Research Directorate, Air
Force Cambridge Research Laboratories, Office of Aerospace
Research, with the Cooperation of the Lowell Technological
Institute Research Foundation
Edited by
WILLIAM G. CHACE
Geophysics Research Directorate
Air Force Cambridge Research Laboratories
Office of Aerospace Research
and
HOWARD K. MOORE
Lowell Technological Institute Research Foundation
PLENUM PRESS
NEW YORK
1962
ISBN-13: 978-1-4684-7507-4 e-ISBN-13: 978-1-4684-7505-0
DOl: 10.1007/978-1-4684-7505-0
Library of Congress Catalog Card Number: 59-14822
Softcover reprint of the hardcover 1st edition! 1962
PREFACE
This volume contains the proceedings of the Second Conference
on the Exploding Wire Phenomenon. In addition to the general theory
of exploding wires, this conference considered exploding wire
shock waves; the generation by exploding wires of extreme tem
peratures, X-rays, and very high pressures; instrumentationprob
lems in wire explosions; and, for the first time, exploding foils.
Sponsored by the Geophysics Research Directorate ofthe Air Force
Cambridge Research Laboratories, this symposium was held in
Boston, Massachusetts, on November 13 and 14, 1961.
To fill a definite need for ready access to information, Volume
Two of Exploding Wires contains a comprehensive index which should
facilitate the use of both volumes on the exploding wire phenomenon.
It is not possible to express full appreciation to all those whose
generous assistance made the Second Conference and this volume
possible. It is certain, however, that without the cooperation of
Dr. John N. Howard, Laboratory Chief, and Mr. Morton A. Levine,
Branch Chief, there could have been no conference. Special ac
knowledgment goes to the Staff of the Hydromagnetics Laboratory
for its invaluable aid: to Mrs. William Watson for exceptional
secretarial work; to Mr. E. H. Cullington for technical assistance;
to Mr. C. V. Fish for drawings, graphs, and art work; and to Mr.
K. R. Saari for photography. Particular gratitude is due to Mr.
Henry Novak for assuming the administration ofthe very successful
day of post-conference seminars at the L. G. Hanscom Field at
Bedford, Massachusetts.
CONTENTS
Introduction . " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " 1
William G. Chace
GENERAL PAPERS
Factors Affecting the Time to Burst in Exploding Wires 5
Charles P. Nash and Clifford W. Olsen
Recent Contributions to the Macroscopic Analysis of Con-
ducting Electromechanical Solids . • . . . . . • • • • • • • • 15
R. C. Geldmacher
A Hydrodynamic Explanation for the Anomalous Resistance
of Exploding Wires. • • • • • • • • • • • • • • • • • • • • • • • • 21
Robert J. Reithel and J. H. Blackburn
Lower-Upper Bounds of Temperatures for Wires Exploded
in a Vacuum" " " " " " " " " " " " " " " " " " " " " " " " " " " " " 33
Carl A. Rouse
The Electrical and Optical Properties of Rapidly Exploded
Wires """"""""""""""""""""""""""""""""" 37
Francis H. Webb, Jr., Henry H. Hilton, Paul H. Levine,
and Alvin V. Tollestrup
About Distances in the "Characteristic Pattern" of Exploding
Wires """".,,""""""""""""""""""""""""""" 77
Heinrich Arnold and William M. Conn
Exploding Wires as a Source of X Rays. • • • • • • • • • • • • • 87
I. M. Vitkovitsky, P. P. Bey, W. R. Faust, R. Fulper, Jr.
G. E. Leavitt, and J. D. Shipman, Jr.
Calorimetric Calibration of the Electrical Energy Measure-
ment in an Exploding Wire Experiment ••••••••••• 97
D. H. Tsai and J. H. Park
Effects of Transmission Lines in Applications of Exploding
Wires """"""""""""""""""""""""""""""""" 109
R. Carroll Maninger
SHOCK WAVES
Microwave Doppler Measurements of the Ionization Front
in Cylindrical Shock Waves from Exploding Wires. • • • 127
Donald L. Jones and Roger M. Gallet
Electrical Generation of Imploding Shock Waves. • • • • • • • 145
R. S. Dennen and L. N. Wilson
...........
Blast Waves Produced by Exploding Wires 159
Koichi Oshima
Exploding-Wire-Driven Shock Waves • • • • • • • • • • • • • • • 175
G. L. Clark, J. J. Hickey, R. J. Kingsley,
and R. F. Wuerker
Shock Waves from Exploding Wires at Low Ambient Densities 181
F. D. Bennett and D. D. Shear
APPLICA nONS
The Use of Exploding Wires in the Study of Small-Scale
Underwater Explosions. • • • • • • • • • • • • • • • • • • • • • 195
R. R. Buntzen
Studies of Metal-Water Reactions by the Exploding Wire
Technique. . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. . .. .. .. .. .. .. .. 207
Louis Baker, Jr., and Raymond L. Warchal
Pressure Environments Created by Wires Exploded in Water 225
J. A. Kersavage
An Exploding Wire Hypervelocity Projector. • • • • • • • • • • 235
Victor E. Scherrer
EXPLODING FOILS
High-Speed Cine micrographic Studies of Electrically Ex-
ploded Metal Films •••••••••••••••••••••••• 245
L. Zernow, F. Wright, Jr., and G. Woffinden
Exploding Foils-The Production of Plane Shock Waves and
the Acceleration of Thin Plates •••••••••••••••• 263
D. V. Keller and J. R. Penning, Jr.
Acceleration of Thin Plates by Exploding Foil Techniques 279
A. H. Guenther, D. C. Wunsch, and T. D. Soapes
Aerosols from Exploding Wires. . • • • • • • • • • • • • • • • • • 299
F. G. Karioris, B. R. Fish, and G. W. Royster, Jr.
Author Index for Volumes 1 and 2 313
.. .. .. .. .. .. .. .. .. .. .. .. .. III .. .. ..
Subject Index for Volumes 1 and 2 .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 315
INTRODUCTION
William G. Chace
Geophysics Research Directorate
Air Force Cambridge Research Laboratories
Bedford, Massachusetts
Progress in the field of exploding wires since the First Con
ference on the Exploding Wire Phenomenon in 1959 and the publi
cation of Volume 1 of this series [1] can best be described as
healthy growth. There have been no startling disclosures on the
theoretical side, and no newly suggested application could be called
a "breakthrough." However, the study of exploding wires is develop
ing into a recognized area of physics. It is no longer necessary to
be apologetic about one's work in this field, as it was only a few years
ago. A review of this growth in four areas seems appropriate.
C LASSIFICAT ION
It has finally come to be realized that all "exploding wires" are
not the same. In earlier work, wire explosions were thought to differ
only in degree, and a single theoretical model was sought. It is now
generally recognized that under different conditions, different phe
nomena may become the controlling factors, producing quite different
explosion mechanisms. Thus it appears that in very fast, high-energy
explosions certain factors which are dominant in slow explosions
just never have time to become important. In a similar manner, the
peripheral arcs so important at reduced pressures may never
develop at all at a pressure of 1 atm.
Although there is a general recognition of the difference between
various wire explosions, the question of a suitable method of classi
tying has not yet been answered.
Several classification schemes have been suggested, one by Webb
et al. [2] and one by Chace and Levine [3].
The Chace and Levine scheme is based upon rate of energy
delivery to the wire. Four classes are proposed:
Melting -the available energy is less than that necessary for
complete vaporiation. Thus,
2 William G. Chace
(1)
where C is the capacitance ofthe storage capacitor, Vo is the original
potential on the condenser bank, IVv is the energy required to vapor
ize the wire, I is the currentthrough the wire, and Ro is the effective
resistance of the discharge circuit.
The wire here never vaporizes, but breaks up into droplets, or
simply burns through. This is fuse behavior.
Slow Explosion -the time required to vaporize the wire is long
compared with the time required for instabilities to develop in the
melted wire. Thus,
(2)
where tv is the time required to vaporize the wire, 1/1 is the time
constant of instabilities, i.e., the time required for instabilities
(e.g., unduloids) to double in magnitude. Referred to explosion be
havior this means that the explosion occurs slowly enough so that
physical distortions have a significant effect on the manner in which
the explosion occurs.
Fast Explosion -the time to vaporize is small compared with the
time constant of instabilities. Thus,
(3)
Referred to explosion behavior this means that the explosion occurs
so quickly that no significant changes in shape occur.
Explosive Ablation* -the time to vaporize is small compared with
the electrothermal time constant. Thus,
(4)
where (; is the electrothermal time constant, i.e., the time for a
temperature equal to the boiling point to penetrate to a depth of
r/ e, where r is the original wire radius and e is the base of natural
logarithms. In terms of explosion behavior the wire vaporizes in a
thin surface film before the center has become heated. In other
words, the "skin effect" controls the behavior.
In Webb's classification system, the rate of energy delivery is
also a controlling factor, but his reference time is time for a sonic
wave to go to the center of the wire and return.
The need for a classification is thus apparent.
"'Note that the term "ablation" is used differently here and by Webb.
William G. Chace 3
QUANTITATIVE DATA
The second factor which has contributed to an improved theo
retical position in the field is the improvement in instrumentation
methods with a resultant increase in quantitative data. This of course
is normal for a young and developing discipline. It will be observed
that the percentage of purely qualitative papers has dropped from
32% in Volume 1 to 14% in Volume 2.
The methods used to measure current and voltage are being
given careful consideration by experimenters today. It has become
apparent that a simple shunt and voltage divider do not suffice in an
E.W. experiment. The findings of all careful experimenters have
proved that the spurious signals from all but the most carefully
designed transducers are likely to override the desired signal com
pletely. Even the ftold standby, ft the Park coaxial shunt, is being
reevaluated (see Tsai and Park [4] and Chace and Levine [5]). Thus
with more confidence in our ability to make measurements, quanti
tative studies are becoming more common and more meaningful.
COMMUNICATION
Another trend in the E. W. field, a trend which has particularly
accelerated in the two-year period under consideration, is that of
freer communication. This is most noticeable in the large number
of significant uses discussed at the second conference. Although
some uses were reported in 1959, each represented a quite spe
cialized type of use (e.g., Schiff [6] and Janes and Koritz [7]. Those
reported in the present volume are of a more general type, such as
generation of x rays and generation of very high pressures (over 70
kilobars) for test purposes. There thus appears to be an increasing
deSire, on the part of government and commercial laboratories
alike, to report E. W. results. This is certainly a healthy trend for
the growth of the discipline.
EXPLODING FOILS
A newcomer in the general field is the exploding foil. Its similar
ity to the exploding wire is so great that it obviously belongs in our
area, but it is sufficiently different to add new depth to the science.
Possibly we should be prepared to rename this branch of physics the
ftexploding conductorft rather than the ftexploding wire ft phenomenon.