Development of a small-sized apparatus for hypervelocity impact experiment in a standard-scale laboratory of one unit

二级轻气炮是唯一能够以良好的再现性加速小型弹丸超过3公里/秒的发射装置。由于该发射装置的安全操作和对环境的沉默，需要在与其他设施隔离的大型实验室中安装。然而，一个非常小的两级光气枪，即所谓的微枪，可以设计成一个午餐器，设置在一个标准规模的实验室30平方米的地板表面。它成功地建立在一个只有2.8分钟长度的基础上。该炮的发射管和压缩管尺寸易于修改，对弹丸加速度有较好的影响。发射管和压缩管的内径分别为1.58毫米和9毫米，用于标准操作。这种选择的原因之一是市场上的高压管可以用作这些管。采用磁-飞法对弹丸速度进行了简单、精确的测量。这种方法需要制备铁磁材料的弹丸。由此制备出质量密度为5.1 g/cm^3、直径为1mm的球形MnAl合金弹丸。每个发射体都被放入一个尼龙制成的弹壳中，作为发射管中的飞行器。对部分参数进行了如下加速度实验；装药量，设置在发射管和高压联轴器之间的隔膜的厚度，用于轻气体压缩的活塞的重量，以及弹丸的重量。实验结果表明，该微型二级轻气炮利用安全氦气可使弹丸加速至5 km/s，研制成功。

Atwo-stage light gas gun is the only launcher which can accelerate a small projectile over 3 km/s with good reproducibility. This launcher needs to be set up in a large-scale laboratory isolated from other facilities because of its safety operation and silence for environment. However a very small-sized two-stage light gas gun, so called a micro gun, could be designed as a luncher to be set up in a standard-scale laboratory of 30 m^2 in floor surface. It was successfully constructed on a base of only 2.8 min length.This gun was designed to be modified easily in sizes of its launch tube and compression tube which act effectively on projectile acceleration.The launch tube and compression one have the inner diameters of 1.58 mm and 9 mm, respectively for standard operation.One of reasons for this selection is that high-pressure tubes on the market can be used as these tubes.A magne'to-flyer method was adopted for simple and precise measurement of projectile velocity.A projectile made of ferromagnetic material needs to be prepared for this method.Thus, sphere-shaped projectiles of MnAl alloy with mass density of 5.1 g/cm^3 and diameter of 1mm were made.Each projectile was put in a sabot made of nylon as a flyer in the launch tube.Acceleration experiments were conducted with respect to some of the parameters as follows ; amount of charge, thickness of a diaphragm set between the launch tube and a high-pressure coupling, weight of a piston for light-gas compression, and weight of a projectile.Experimental results showed that this micro two-stage light gas gun can accelerate a projectile up to 5 km/s by using of safety helium gas, and that this gun was successfully developed.