Showing papers on "Projectile published in 1989"

Multiple-ionization collision dynamics

Abstract: The 1.4-MeV/u U/sup 32 +/+Ne collision system is studied in detail in order to elucidate the dynamics of multiple ionization in energetic, heavy-ion--atom collisions. Differential cross sections versus recoil-ion charge state, calculated by the /ital n/-body classical-trajectory Monte Carlo method, are presented for the theta and /ital cphi/ angle dependences of the projectile, recoil ion, and ejected electrons. The calculations show a high degree of ejected-electron asymmetry towards the projectile side of the target nucleus which strongly effects the transverse-momentum balance between the heavy particles. Experimental and calculated cross sections differential in the recoil-ion charge state and transverse momentum are found to differ by orders of magnitude from those for the projectile, providing evidence for the importance of explicitly considering the ejected electrons' momenta in the determination of the heavy-particle (both the projectile and the recoil-ion) angular differential cross sections. Polarization of the target electrons and screening of the recoil ion by the ejected electrons lead to /similar to/10/sup /minus/6/-rad negative-angle deflections of the projectile for recoil-ion charge states up to 4+. The angular scattering of the recoil ion departs significantly from that predicted for a two-body collision, and is found to be nearly isotropic for low recoil-ion charge statesmore » and peaked to angles theta/gt/90/degree/ for high recoil-ion charge states. A stopping-power calculation for this system is in good agreement with the experimental value. Stopping powers differential in impact parameter and for energy deposition to delta electrons and multiple ionization are given to further describe the projectile energy loss.« less

Concerning the design of capacitively driven induction coil guns

Abstract: The authors consider the design of capacitively driven, multisection, electromagnetic coil launchers, or coil guns, taking their transient behavior into account. A lumped-parameter computer simulation is developed to predict the performance of the launcher system. It is shown that a traveling electromagnetic wave can be generated on the barrel by the resonance of drive coils and their capacitors. More than half of the energy initially stored in the capacitor bank can be converted into kinetic energy of the projectile in one shot, and an additional quarter can be utilized in subsequent shots, if the launcher dimensions, resonant frequency, and firing sequence are properly selected. The projectile starts smoothly from zero initial velocity and with zero initial sleeve current. Section-to-section transitions which have significant effects on the launcher performance are also discussed. Experimental results were obtained with a small model and are in good agreement with theoretical predictions. >

Optical fiber guided tube-launched projectile system

Abstract: An optical fiber-guided projectile (20) launch system for firing from a generally tubular launcher comprising a projectile (20) having tubular casing (22), an extended length of optical fiber (44) disposed in the casing (22) for continuous streaming from the trailing end thereof (26), a portion of the fiber (44) extending from the casing (22) for operative connection to a controller (58), an axial groove (52) in the casing surface for removably receiving a part of the extending fiber, tape (64) securing the fiber part in the groove (52) with force sufficient to withstand axial launch forces but insufficient to resist imposed radial forces, and a communication device providing two-way communication over the fiber (44) An alternative embodiment uses an un-grooved projectile casing with a tube launcher having a preformed fiber relief-groove in the inner peripheral surface and a discarding sabot having a tab member receivable in the relief For both embodiments, a controller (50) is provided in two-way communication with the projectile (20) for receiving and processing target data from the projectile (20) and for transmitting guidance data, including operator manual guidance, to the projectile (20), and an adaptor is provided for guiding fiber streaming axially from a wound bobbin in the projectile

Helium ionisation by high-energy ions at a function of impact parameter and projectile scattering angle

Abstract: The author considers the single ionisation of helium by ions in the Born approximation. The target initial and final states are represented by Hartree-Fock-Slater functions. The author calculates the ionisation probability for a given impact parameter as a function of the energy and ejection angle of the electron. A similar work is also carried out as a function of the projectile scattering angle. The author shows that the projectile scattering is determined by both the projectile-electron and projectile-target-nucleus interactions for scattering angles of the order of 1 mrad. For these small angles, there is no simple relation between the variation as a function of impact parameter and scattering angle.

Computational investigation of oblique detonation ramjet-in-tube concepts

Abstract: Ramjet-in-tube techniques have been proposed to accelerate masses up to thousands of kilograms to velocities of 0.7-12.0 km/s by chemical means. CFD calculations for three oblique detonation ramjet-in-tube drive modes are presented; the operational velocities for the present results range from 3.5 to 10.0 km/s. The first drive mode achieves ignition on the reflection of the nose cone bow shock. The second drive mode relies on a sudden, steep, but small increase in projectile radius to initiate a detonation wave, following a deliberately gentle, gradual compression process. The third drive mode is similar to the second mode except that the projectile is thermally protected by flying it through a core of pure hydrogen gas surrounded by a detonable mixture. At optimum operating conditions, the thrust pressure ratios (defined as the effective thrust pressure divided by the maximum cycle pressure) for the three modes range from 0.12 to 0.30, and the efficiencies (defined as the thrust times the velocity divided by the rate of chemical energy release) range from 0.09 to 0.26. Tables of thrust pressure ratios and efficiency data and representative plots of the pressure fields around the projectiles are presented.

Penetration and ricochet phenomena in oblique hypervelocity impact

Abstract: An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectile on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

Design and power conditioning for the coil-gun

Abstract: The author describes the power conditioning scheme for a contactless coilgun called the linear induction launcher (LIL). The barrel of the LIL consists of a linear array of coils carrying polyphase currents. These create an electromagnetic wave pocket which moves with increasing velocity from breech to muzzle, smoothly accelerating a conductive sleeve which carries a set of azimuthal currents sinusoidally distributed along its length and which encloses the projectile payload. The power conditioner provides high energy utilization by transferring energy from capacitor to capacitor simultaneously with the projectile movement. The modular construction of the barrel is described together with laboratory results obtained with a breadboard model of the power conditioner circuit. >

Evidence for electron-electron interaction in projectile K-shell ionization.

Abstract: Cross sections for projectile {ital K}-shell ionization were measured for 0.75--3.5-MeV/{ital N} C{sup 5+} and O{sup 7+} projectiles in collisions with H{sub 2} and He targets. The experimental results agree with plane-wave Born-approximation calculations which take into account the interaction between projectile and target electrons. We demonstrate that for energies where the target electrons have sufficient kinetic energy in the projectile frame to ionize the projectile electron, the electron-electron interaction can lead to a significant increase in the total ionization cross section.

High-pressure having plasma flow transverse to plasma discharge particularly for projectile acceleration

Abstract: A projectile is accelerated through a gun barrel in response to high pressure gas applied to the rear of the projectile in response to a high pressure plasma discharge. Plasma from the discharge flows transversely of the discharge into a chamber through multiple openings in a passage wall that confines the discharge. The high pressure, high temperature plasma flowing into the chamber causes an exothermic reaction of water and metal particles in a slurry in the chamber to produce high pressure hydrogen gas that flows longitudinally of the discharge against the rear of the projectile. To maintain the pressure of hydrogen gas acting against the projectile relatively constant as the projectile is accelerated down the barrel, electric power applied to the discharge increases substantially linearly as a function of time.

Friction and ablation measurements in a round bore railgun

Abstract: Detailed experiments were performed in order to determine electrode ablation and friction effects in a round-bore railgun. An accelerating model was developed which includes electrode-ablation effects, the viscous arc drag, and the mechanical friction of the projectile. In addition, a novel nonlinear electrode-ablation model was found to describe the experimental data very well. A model for the mechanical friction force between the projectile and bore wall was applied to the equation of motion. The position/time data of the projectile acceleration could be adjusted with quite reasonable friction effects. Theoretical and experimental results show that the 'ideal' projectile velocity is decreased by about 28%: 15% due to electrode ablation, 9% due to mechanical friction, and about 4% due to viscous arc drag. >

The effect of rail resistance on railgun efficiency

Abstract: A time-dependent model of rail resistance based on one-dimensional current diffusion was developed and implemented in a railgun simulation code that can be used to study efficiency and losses in most railgun systems. Results were obtained for simple 500 kA, 2-m gun using metal armature. It is shown that typically 25% of the energy delivered to the gun is dissipated in rail resistance. The energy lost in the rails is about 75% of the final kinetic energy of the projectile. Gun efficiency can be improved by about 7% by simply cooling the rails to 77 K. Resistive voltage drop in the rails accounts for 33% of the breech voltage. Performance as measured by muzzle velocity depends on available power supply energy. >

Observation of electron-electron scattering in electron capture by fast protons from He.

Abstract: The angular distribution of electrons ejected from He with about the projectile velocity in coincidence with the capture of the other electron by the projectile in 1-MeV proton-He collisions has been measured. The signature of the proton-electron-electron scattering leading to transfer ionization has been observed for the first time as a peak at about 90{degree} in the angular distribution of the ejected electrons. The effect is in qualitative agreement with theoretical predictions.

Aerodynamic air foil surfaces for in-flight control for projectiles

Abstract: Aerodynamical air foil surface and subsurface expressions and/or impressions of varied geometrics, angles of attack, heights and depths, comprising part of a projectile surface itself to create McClain effect molecular friction/pressure/temperature reaction flight control surfaces which automatically achieve in all fluids and velocities of flight self-stablizing spin and rotation, increased height of trajectory with corresponding enhancement of range and distance, kinetic energies, inducing smooth laminar boundary layer flows, substantially decreasing drag effects, synergistically combined to constitute a major technological improvement in performance of all projectiles.

Anti-material projectile

Abstract: An anti-material projectile of trangible alloy for fragmenting due to impact shock on hitting a target thereafter penetrating the target causing damage. The projectile is preferably high density frangible alloy having a ratio of compressive to tensile strength of 20 to 1. The projectile is useful against soft targets suct as aircraft as well as armor targets where initial impact is at the armor plating. The projectile may be a composite of pyrophoric windscreen with a projectile body of frangible alloy and armor piercing alloy.

Neutralization of fast alkali-ions after grazing scattering from Al(111) and Ni(111)

Abstract: We have studied the neutralization of fast Na+- and K+-ions after the interaction with clean and flat Al(111)- and Ni(111)-surfaces at grazing incidence Φ < 1°. The neutral fractions of specularly reflected projectiles show two different classes of dependences on projectile velocity which can be referred to the difference between work function of the target and binding energy of the atomic ground term. Model calculations in the framework of resonance tunneling between metal surface and atom which incorporate the parallel velocity of the projectile by Galilean-transformation and the electronic spin degree of freedom reproduce our experimental data fairly well.

Advanced compulsators for railguns

Abstract: In order to maximize the penetration of a projectile into a target, the acceleration on the projectile during the launch must be minimized. Low accelerations permit the design of long and slender projectiles which have better penetration capability. From this standpoint, power supplies for electromagnetic launchers must be able to provide rectangular current pulses with a high average to peak acceleration ratio. The authors discuss efforts to obtain the desired pulse shape from a compensated pulsed alternator (compulsator) when it is used as a power supply for railguns. A general theory of the pulse shaping technique is presented first. This is followed by a discussion on the tradeoffs between various equivalent generator configurations. Finally, the electromagnetic design of the compensated pulsed alternator being developed for task C of the Electromagnetic Gun Weapons System Program is presented. >

Non-ricocheting projectile and method of making same

Abstract: A practice projectile for use with military aircraft and the like for training pilots in attacking ground targets comprises a unitary body formed of sintered sponge iron powder and having a sintered density equivalent to the apparent density of a projectile to be simulated.

An apparatus for determining roll position

Abstract: An apparatus for determining the roll position of a spinning projectile with the aid of polarized electro-magnetic radiation comprises a transmitter for emitting polarized radiation in a direction towards the projectile and a polarization-sensitive receiver disposed in the projectile for receiving the polarized radiation. The polarized radiation emitted from the transmitter has an asymmetric wave-form which is formed by superimposing at least two mutually phase-interlocked radiation components of the wavelength relationship of 2:1 and/or multiples thereof, and the polarization-sensitive receiver includes a single receiver antenna.

Design and testing of large-bore, ultra-stiff railguns

Abstract: As part of an EM (electromagnetic) gun technology demonstration program, a systematic design approach targeted at identifying critical gun design constraints affecting hypervelocity projectile performance has been pursued. Results of the study led to a laboratory-based EM gun design that provides bore straightness and tolerances characteristic of light-gas guns, dynamic bore deformations comparable to those of conventional guns, the ability to change and test rail/sidewall insulator materials quickly, and superior in-bore performance diagnostics. A high-stiffness, easily maintained, precision-bore 9-MJ EM launcher has been designed and fabrication is virtually complete. A half-scale prototype of this hydraulically prestressed EM gun design has been fabricated and successfully tested. The authors discuss the railgun design approach and performance parameters, the analytical and empirical railgun structured simulation techniques used to validate the full scale gun design, and the fabrication status and initial performance test results. >

Target seeking projectile

Abstract: A projectile for launching by a cannon or by a launcher is obtained by an expedient combination of features. An optical seeker has a gyro mounted on an air bearing and an optical detector. a Cassegrain system is arranged on the gyro as imaging optical system and scans a field of view with a gyrating scanning motion. At its tip, the projectile is closed by an optically transparent wedge, which is limited by planar surfaces. The optically transparent wedge carries a central spike. The projectile has tail stabilizing fins and steering by wings arranged near the center of gravity of the projectile. The wings are controlled by signals from the detector through signal processing means and an actuator system. The projectile is shaped make a continuous roll movement due to aerodynamic forces.

Influence of ionised electrons on heavy nuclei angular differential scattering cross sections

Abstract: For the collision systems 1.4MeVu-' U3'+ and 5.9 MeVu-' U65+ on Ne, transverse (with respect to the beam axis) momentum distributions of recoiling target atoms have been measured applying a time-of-flight technique. In the case of isotropic electron emission, the transverse momenta of the recoil ion pRL and the projectile ppl after the collision are identical. This allows the transformation of measured pRl distributions into projectile related differential scattering cross sections du/d8. Using such an analysis, we have measured differential cross sections in the scattering angle regime of 1 x rads 8 G 4x rad. The shape, as well as the absolute magnitude of the derived experimental da/d8 is in reasonable agreement with Rutherford differential cross sections at large 8 using a projectile nuclear charge of 2, = qp and a target nuclear charge of Z, = 5. For 8 6 1 x rad, n-body classical trajectory Monte Carlo (nCTMC) calculations predict that the balance between pRl and ppI is strongly influenced by the momenta of anisotropi- cally emitted ionised electrons. From the comparison between the derived experimental cross sections da/d8 with the theoretical values, as well as from the agreement between experimental and theoretical transverse recoil-ion momentum distributions, we conclude that the momenta of the ejected electrons have a considerable influence on the scattering dynamics of the heavy nuclei. Furthermore, the calculations indicate that the projectile is scattered to negative angles at impact parameters of b 3 3a0 due to anisotropic electron emission and strong polarisation of the target electron cloud by the Coulomb potential of the projectile. The possibility of rainbow scattering at 8 = 1 x rad is predicted.

Projectile angular dependence of the ratio of double to single ionization produced by fast protons in collision with helium.

Abstract: We suggest an explanation for the structure, observed by Giese and Horsdal, in the projectile angular dependence of the ratio of double to single ionization produced by fast protons in collision with helium. We postulate that two incoherent mechanisms, a first that produces slow electrons and a second that produces fast electrons, combine to give the effect.

Handheld water balloon catapult

Abstract: A catapult having traditional slingshot components implementing a yolk of greater clearance, thus allowing an enlarged projectile pouch to be attached These features allow projectiles, of greater mass such as water balloons, to be launched with considerable accuracy and distance Combined with the above described catapult is a guard which protects fingers from the occasional contact which may occur during projectile launch

Production of helium (Z=2) projectile fragments in 16O-emulsion interactions from E/A=2 to 200 GeV.

Abstract: The fragmentation of relativistic $^{16}\mathrm{O}$ projectiles in nuclear emulsion into projectile fragments of Z\ensuremath{\ge}2 has been investigated. Production rates, charge, and multiplicity distribution of such projectile fragments and their dependence on target-fragment multiplicities have been obtained. The width of the momentum distribution of He (Z=2) projectile fragments as well as the average number of target fragments is found to decrease with increasing He multiplicity. These dependences are, within errors of measurement, the same for E/A=2.1, 14.6, 60, and 200 GeV, and to that extent satisfy the condition of limiting fragmentation.

Coincidence measurements of slow recoil ions with projectile ions in 42-MeV Ar q + -Ar collisions

Abstract: Slow Ar recoil-ion production cross sections by projectiles of 1.05-MeV/amu ${\mathrm{Ar}}^{\mathrm{q}+}$ (q=4,6,8,10,12,14) were measured using a projectile-ion\char21{}recoil-ion coincidence technique. The present results indicate that the average recoil ion charges 〈i〉 increase with increasing the incident projectile charge q and the number of the lost and captured electrons from and/or into projectiles, whereas the projectile charge-changing cross sections for loss ionization decrease steeply with increasing q for low-charge-state projectiles, and those for transfer ionization increase rapidly with increasing q for high-charge-state projectiles. For Ar projectiles with q=10, which corresponds to the equilibrium charge state of Ar projectiles at the present collision energy, the average recoil-ion charges are nearly the same in both loss and transfer ionization, and a pure ionization process plays a much more important role in producing highly charged recoil ions, in contrast to projectile electron loss or transfer processes, which play a role in other projectile charge states.

Apparatus for setting a projectile time fuze

Abstract: An apparatus for setting a time fuse in a projectile, with the muzzle velocity of the projectile being measured and its delay being corrected by the value measured for the muzzle velocity. To determine the muzzle velocity of the projectile, the latter is provided with a magnetic field sensor and the gun barrel is provided with two magnetic axially spaced field generators adjacent its muzzle. The magnetic field sensor is connected, via an amplifier, to a start/stop counter which starts counting clock pulses when the projectile flies past a first of the magnetic field generators and stops counting clock pulses when the projectile flies past the other of the two magnetic field generators to provide a final count which is a measure of the projectile muzzle velocity. The final count of the start/stop counter is then used to adjust the counter clock pulse frequency which is then used by further circuitry, e.g. a preset backward counter, to provide the delay for the fuze.