Hypervelocity Launch Research Articles

Numerical Simulation of Hypervelocity Launch Process of Cased Telescoped Ammunition Armor-piercing Projectile

In order to study the interior ballistic characteristics of cased telescoped ammunition (CTA) armor-piercing projectile in the hypervelocity launch process, in this paper, based on the secondary ignition and propellant combustion technology, the zero-dimensional internal ballistic model of CTA is established. At the same time, in order to improve the lightweight of CTA and the energy utilization rate of the launch process, combustible cartridge materials are applied to the structure of cased telescoped ammunition. Numerical simulation of 105 mm CTA grenade shooting experiment has verified its correctness. On this basis, the internal ballistic process of 105 mm CTA armor-piercing projectile with semi-combustible cartridge is predicted and analyzed. When main charge propellant weight is 6 kg, the maximum pressure is 569.5 MPa and the muzzle velocity can reach 1702 m/s.

A 200 kJ electrical gun for hypervelocity launch.

In order to meet the requirements of hypervelocity launch in the context of defending against space debris and deflecting asteroids, an electrical gun with 200 kJ of storage energy was recently built. The electrical gun is composed of 16 gas spark switch-capacitor modules, and pulse current is transmitted by parallel aluminum plates that are insulated by polyester foils. The capacitance, inductance, and resistance of the RLC circuit of the 200 kJ electrical gun are 80 µF, 10.3 nH, and 2.6 mΩ, respectively. It can generate pulse current with a rise time of 1.33 µs and an amplitude of 5.2 MA when short-circuited at a charging voltage of 70kV. Hypervelocity flyer launch experiments were carried out on the 200 kJ electrical gun, in which a ϕ20 × 0.5mm2 Mylar flyer (0.22g) was accelerated to 10 km/s.

Effect of injection pressure on the plasma-liquid interaction in a stepped-wall liquid chamber

The electrothermal chemical launch is a new concept hypervelocity launch technology that the propellant is ignited by high-temperature plasma. Understanding the heat and mass transfer mechanism between plasma and liquid and choosing a reasonable injection pressure is crucial for a reliable launch. Experimental and numerical studies are carried on to investigate the plasma-liquid interaction mechanism, as well as the effect of injection pressures ranging from 2 MPa to 8 MPa. As plasma expands in a stepped-wall chamber, the plasma jet's axial penetration speed is decreasing and the surface area is increasing linearly. The plasma front surface varies from an arc shape to a cone shape, and the necking phenomenon forms near the step. Vortexes generated in the interaction flow field are divided into four categories. There is intensive pressure variation near the nozzle and a pressure peak in the pressure decrease region. Besides, increasing the injection pressure enhances the plasma expansion ability and promotes the phenomena which increase the plasma surface. However, increasing the injection pressure aggravates the flow field instability. Formulas for estimating the plasma jet's axial penetration distance and surface area growth rate are summarized for choosing a reasonable injection pressure.

The Launch Performance Analysis of the Electromagnetic Coil Launcher Continuous Launch Process With Multiple Armature

In this paper, it is mainly aimed to study the working condition when there exists multiple armatures in launch tubes in the process of hyper velocity launching of the electromagnetic coil launcher. On the basis of understanding the single stage induction coil launch principle, this article expounds the working process of this kind of condition, and based on the circuit principle, an electrical and mechanical model for continuous emission of electromagnetic coil launcher with multiple armatures is set up. Through systematic description to the launcher equivalent circuit and the control equation, thrust equation and equation of motion, it further expounds the mechanism of the launcher. Dynamic simulation and structural design of electromagnetic coil launcher is conducted based on established parameters. Finally, the results of theoretic analysis and simulation design were further verified by the experiment, and the results of this paper are achieved.

An Improved Impactor Design for Eliminating Spallation in High-Impedance Flyers During Hypervelocity Launch

Spallation in a high-impedance tantalum flyer was confirmed by using a specially designed hypervelocity launch (HVL) experiment, thereby indicating that the conventional flyer was unsuitable for equation of state (EOS) research on materials under ultra-high pressure. Based on the analysis and interpretation of the experimental data and the spallation’s reproduction via a high-fidelity detonation and shock (HDS) wave code, two possible methods to eliminate the spallation were proposed: (1) changing the impactor structure, which could greatly reduce spallation, and (2) altering the impactor material, which could completely eliminate the remaining spallation. We conducted a set of HVL experiments with an improved impactor design in which a high-impedance tantalum flyer was accelerated up to 10 km/s, and no spallation was found, demonstrating the effectiveness of the improved method for performing EOS research on materials under pressures of terapascals loaded by a three-stage light gas gun.

Hypervelocity launching of flyers at the SG-III prototype laser facility

Experiments of laser-driven hypervelocity flyers have been conducted at the SG-III prototype laser facility. Using the continuum phase plate technique, four laser beams each with a 3-ns quadratic profile are configured to produce relatively uniform irradiated spots of diameter size either 500 μm or 2000 μm. With the former, specifically designed multi-layered flyers (polyimide/copper) were accelerated by shock impedance and reverberation techniques via direct laser ablation to a super-high averaged velocity of 55 km/s, much faster than recently reported results. Light-emission signals of shock breakout and flyer impact on flat or stepped windows were obtained that indicated good planarity and integrity for the flyer. In the latter, single-layered aluminum flyers were gradually accelerated to a terminal velocity of 11 km/s, as measured by optical velocimetry, without melting and vaporization. The results suggest that the SG-III prototype laser facility has the capability to launch high-speed flyers to create extreme conditions for investigating the science of shock compression and its equation of state.

Generalized Scaling Laws of Plasma Parameters in Electrothermal Plasma Sources for Fusion Disruption Erosion and Hypervelocity Launch Applications

Generalized operational scaling laws have been developed for the peak plasma parameters at the exit of an electrothermal plasma capillary discharge. These parameters are the total ablated mass, plasma kinetic temperature, pressure, bulk velocity, and the radiant heat flux. The obtained scaling laws have particular coefficients depending on the material of the ablating liner inside the capillary source. The generalized scaling laws include the magnitude of the peak discharge current, material property, and the dimensions of the ablating sleeve. The values given by the scaling laws are compared with the ones calculated by the computational ElectroThermal Flow (ETFLOW) code and against the experimental data. The obtained results of the scaling laws have shown low error, especially the scaling laws of the kinetic temperature and the plasma exit velocity.

Dynamic Simulation and Experimental Research of High Pressure Pneumatic Valve in Gas-Driven Light Gas Gun

Use gas-driven light gas gun is one of the techniques extensively used to achieve hypervelocity projectiles. The device was made up of a compressed gas gun as the first-stage drive. A new type high pressure pneumatic injecting system of gas-driven light gas gun for hypervelocity launching is introduced. As a critical component of the injecting system, the high pressure pneumatic valve was designed. Functions of the pneumatic valve were preserved and relevant techniques were discussed. Besides, a high pressure pneumatic mass flow control test-bed using inert medium was built in order to study the dynamic response characteristic of high pressure pneumatic valve in gas-driven light gas gun. To ascertain the response delay time of the valve, several turn-on and turn-off experimental tests of the valve were initiated. The results suggest that: the pressure of pneumatic electromagnetic valve gas supply circuit seriously influenced the properties of high pressure pneumatic valve; the mean delay time of the high pressure pneumatic valve was 190ms approximately at 6.5MPa gas pressure of the pneumatic electromagnetic valve gas supply circuit.

Thermal calibrations of hypervelocity capture in aerogel using magnetic iron oxide particles

Due to its extremely high porosity and the nanoscale filaments that make up its structure, aerogel is an excellent material for the capture of hypervelocity, micron-sized particles. A great deal of the kinetic energy of a particle is converted to thermal energy during the capture process, altering or even destroying components of the particle. The studies described here were conducted using aggregate projectiles made up of magnetic sub-micron hematite particles in an attempt to directly measure the temperatures experienced by fine particles during hypervelocity capture in aerogels. When these particles are heated to a temperature above their Curie temperature (675°C) during the capture, they lose their magnetization. Thus, by impact testing these particles in aerogels at different velocities, we were able to determine if individual components of these aggregate particles were heated to a temperature greater than their Curie temperature by observing their magnetization. After impact testing, the particles were extracted from the aerogel, thin sectioned, and observed using atomic and magnetic force microscopy, as well as, electron paramagnetic resonance. Terminal particles for impacts at or above 4.5km/s were still magnetic, while those from the track walls were not. Even terminal particles captured at 6.6km/s were still magnetic. Iron oxide particles coated with silica, to mimic extraterrestrial materials, from track walls captured at 5.47km/s were still magnetic. The study also demonstrated that aggregate projectiles can survive the forces they are subjected to during hypervelocity launch in a light gas gun.

Development of a Linear Implosion-driven Hypervelocity Launcher

A traditional difficulty with high-explosive hypervelocity launching techniques is that extreme loading generally causes hydrodynamic deformation of the projectile either incidentally or by design. The launcher presented in this study uses explosives to operate the pump tube of a two-stage light gas gun via continuous linear implosion. In this configuration, the projectile is cushioned from direct action of the explosives by a light driver gas. The launch cycle is therefore comparable to a conventional two-stage light gas gun but with the shock driven by the rapid linear implosion of the pump tube compressing the gas to a much higher enthalpy. A laboratory scale version of the implosion driven launcher has recently demonstrated the ability to launch a 0.7g projectile to 7.9km/s. This design has successfully been scaled up to launch a 15g projectile to 7.6km/s, a result comparable to large two-stage light gas guns. This study presents the experimental and computational work performed in the ongoing development of this device. The extreme launch conditions lead to a number of unique design considerations, including dynamic confinment of the driver and launcher reservoir, mitigation of the loss of driver gas, and in-bore projectile stability and survivability. These issues are addressed experimentally through a number of focused launcher trials, as well as through the development of a quasi-one-dimensional Lagrangian hydrocode. The development of advanced implementations that involve continuing explosives onto the reservoir and launch tube in order to maintain a high driving pressure are also considered. These “second stage” techniques offer the potential for achieving projectile velocities in excess of 10km/s.

Magnetically driven hyper-velocity launch capability at the Sandia Z accelerator

The intense magnetic field generated by the Z accelerator at Sandia National Laboratories is used as a pressure source for material science studies. A current of ∼20 MA can be delivered to the loads used in experiments on a time scale of ∼100–600 ns. Magnetic fields (pressures) exceeding 1200 T (600 GPa) have been produced in planar configurations. In one application we have developed, the magnetic pressure launches a flyer plate to ultra-high velocity in a plate impact experiment; equation of state data is obtained on the Hugoniot of a material that is shock compressed to multi-megabar pressure. This capability has been enhanced by the recent development of a planar stripline configuration that increases the magnetic pressure for a given current. Furthermore, the cross sectional area of a stripline flyer plate is larger than in previous coaxial loads; this improves the planarity of the flyer thereby reducing measurement uncertainty. Results of experiments and multi-dimensional magneto hydrodynamic (MHD) simulation are presented for ultra-high velocity aluminum and copper flyer plates. Aluminum flyer plates with dimensions ∼25 mm by ∼13 mm by ∼1 mm have been launched to velocities up to ∼45 km/s; for copper the peak velocity is ∼22 km/s. The significance of these results is that part of the flyer material remains solid at impact with the target; an accomplishment that is made possible by shaping the dynamic pressure (current) ramp so that the flyer compresses quasi-isentropically (i.e., shocklessly) during acceleration.

激光驱动飞片超高速发射技术实验研究

激光驱动飞片超高速发射技术实验研究

Bacterial Spores in Granite Survive Hypervelocity Launch by Spallation: Implications for Lithopanspermia

Bacterial spores are considered good candidates for endolithic life-forms that could survive interplanetary transport by natural impact processes, i.e., lithopanspermia. Organisms within rock can only embark on an interplanetary journey if they survive ejection from the surface of the donor planet and the associated extremes of compressional shock, heating, and acceleration. Previous simulation experiments have measured each of these three stresses more or less in isolation of one another, and results to date indicate that spores of the model organism Bacillus subtilis can survive each stress applied singly. Few simulations, however, have combined all three stresses simultaneously. Because considerable experimental and theoretical evidence supports a spallation mechanism for launch, we devised an experimental simulation of launch by spallation using the Ames Vertical Gun Range (AVGR). B. subtilis spores were applied to the surface of a granite target that was impacted from above by an aluminum projectile fired at 5.4 km/s. Granite spall fragments were captured in a foam recovery fixture and then recovered and assayed for shock damage by transmission electron microscopy and for spore survival by viability assays. Peak shock pressure at the impact site was calculated to be 57.1 GPa, though recovered spall fragments were only very lightly shocked at pressures of 5-7 GPa. Spore survival was calculated to be on the order of 10(-5), which is in agreement with results of previous static compressional shock experiments. These results demonstrate that endolithic spores can survive launch by spallation from a hypervelocity impact, which lends further evidence in favor of lithopanspermia theory.

Researches on Hypervelocity Launching by Flier-Plate Materials with Graded Impedance

Researches on Hypervelocity Launching by Flier-Plate Materials with Graded Impedance

Preparation of Flier-Plate Materials with Graded Impedance Used for Hypervelocity Launching

Preparation of Flier-Plate Materials with Graded Impedance Used for Hypervelocity Launching

A 4.5-MJ pulsed power supply for railgun experiments

A 4.5-MJ capacitor-based pulsed power supply (PPS) has been installed at the U.S. Army Research Laboratory (ARL), Aberdeen Proving Ground, MD, for railgun operations. The system consists of 18 independent modules, each with an energy capacity of 250 kJ. Half of the modules were modified from their original condition to a pulse-forming inductance of approximately 24 /spl mu/H, while the remainder maintained their original 60-/spl mu/H inductance. Another modification included a pneumatic-operated shorting system added to enhance the safety of the system. Simulations were conducted for a variety of load conditions using a Spice-based code. Predicted currents and velocities are in reasonable agreement with measured quantities. The complete system allows the electromagnetic launch of hypervelocity launch packages to a downrange distance of 4 km.

A flier-plate material with graded impedance used in dynamic high-pressure physics

By using such flier-plate material, quasi-isentropic compression can be realized. Based on it, hypervelocity launching is further accomplished. As a result, an extremely high dynamic pressure can be obtained in laboratory, offering a practical method for the comprehensive determination of materials behavior, response, equation-of-state and properties in dynamic loading process.

Review of investigations under way on the large-scale TsNIIMASH ballistic facility

The large-scale TsNIIMASH ballistic facility was built in 1992 through modernization of the large shock tunnel. Having 0.5 m caliber, the facility is 200 m long. Each experiment on the facility envisages an explosion of stoichiometric hydrogen-oxygen mixture, up to 300 cub. m by volume. In the air-evacuated ballistic channel 60 m long, the expanding explosion products of the detonating gas mixture boost gyrostabilized steel plates 0.5m in diam which travel along the channel on a magnetic suspension without a mechanical contact with the walls. The case is unique in combining the ballistic facility geometric dimensions with the plate high-precise motion. Results of experiments on graphite crystalline conversion into diamond are given. Investigations to use the shock tunnel for hypervelocity launch of compact projectiles are discussed.

Time-resolved particle velocity measurements at impact velocities of 10 km/s

Hypervelocity launch capabilities (9 – 16 km/s) with macroscopic plates have become available in recent years. It is now feasible to conduct instrumented plane-wave tests using this capability. Successfully conducting such tests requires a planar launch and impact at hypervelocities, appropriate triggering for recording systems, and time-resolved measurements of motion or stress at a particular point or set of points within the target or projectile during impact. We have conducted the first time-resolved wave-profile experiments using velocity interferometric techniques at impact velocities of 10 km/s. These measurements show that aluminum continues to exhibit normal release behavior to 161 GPa shock pressure, with complete loss of strength of the shocked state. These experiments have allowed a determination of shock-wave window transparency in conditions produced by a hypervelocity impact. In particular, lithium fluoride appears to lose transparency at a shock stress of 200 GPa; this appears to be the upper limit for conventional wave profile measurements using velocity interferometric techniques.

Applications of the ion beam technique for investigations of hypervelocity impacts

In the presentation we report on experiments at the Karlsruhe Light Ion Facility KALIF employing high-resolution laser-Doppler velocimetry. The schemes of possible EOS experiments using interferometry and the dynamics and the limiting factors of the ablative hypervelocity launching are discussed as well as advantages of the ion beam technique for investigations in the field of hypervelocity impacts and equations of state. So far, we have accelerated aluminum foils of 10 to 30 μm thickness to velocities beyond 12 km/s. Besides the beam power, the limiting factors for the launching are melting of the accelerated flyer plate as a result of shock-wave heating and the heat transfer from the energy deposition zone. The experiments considered include the Hugoniot measurements and measurements at unloading of shock-compressed state down to the vaporization region. Parameters of shock waves that cause melting of aluminum, copper, molybdenum and titanium in release have been measured with a pulse proton beam on KALIF. A way of measurements in the vaporization region has been tested with explosive facilities.