**3.1 Metallic foil electrically exploding driving highvelocity flyers[24,25,26]**

As descibed above, the high pressure gas and plasma are used to launch highvelovity flyer plates, which are produced from the electrical explosion of metallic foil. The working principle diagram of the metallic foil electrically exploding driving highvelocity flyers is presented in Fig.5. Usually we choose the pure aluminum foil as the explosion material because of its good electrical conductivity and explosion property. The flyers may be polyester films, such as Mylar or Kapton, or complex ones consisted of polyester film and metallic foil. The material of barrel for accelerating the flyers may be metals or non-polyester films, such as Mylar or Kapton, or complex ones consisted of polyester film and metallic foil. The material of barrel for accelerating the flyers may be metals or non-metals, such as

Fig. 5. The diagram of working principle of metallic foil electrically exploding driving flyer.

Magnetohydrodynamics of Metallic Foil Electrical

these two apparatuses.

capacitor

capacitors

Explosion and Magnetically Driven Quasi-Isentropic Compression 355

Fig. 7 shows the photoes of two apparatuses and Table 1 gives the electrical parameters of

(a)

chamber

detonator switch

exploding foil and PMMA barrel

Transmission

line

(b)

Fig. 7. Experimental apparatuses of metallic foil electrically exploding driving flyers. The

apparatus with energy of 14.4 kJ (a) and the apparatus with energy of 40 kJ(b).

ceramics, steel or acryl glass. The base plate is used to confined the high pressure gas and plasma and reflect them to opposite direction to propel the flyers. The base plate also insulates the anode from the cathode transimission lines. So the material of base plate is non-metal and the ceramics is a good one.

The whole working process is that the large current flows through the metallic foil instantly and the metallic foil goes through from solid, to liquid, gas and plasma, and then the high pressure gases and plasmas expand to some direction to drive the polyester Mylar flyer to high velocity and impacts the targets.

Based on low inductance technologies of pulsed storaged energy capacitor, detonator switch and parallel plate transmission lines with solid films insulation, two sets of experimental apparatuses with storaged energy of 14.4 kJ and 40 kJ were developed for launching hypervelocity flyer. The first apparatus is only consisted of one storaged energy pulsed capcitor with capacitance of 32 F, inductance of 30 nH and rated voltage of 30 kV. The parallel plate transmission lines and solid insulation films are used, which are with very low inducatnce. The thickness of insulation films is no more than 1 mm, which is composed of several or ten pieces of Mylar films with thichness of 0.1 mm. The second apparatus is composed of two capacitors with capacitance of 16 F and rated voltage of 50 kV in parallel. For two apparatuses, the detonator switch is used, which is with low inductance of about 7 nH and easy to connected with the parallel plate transmission lines.

Fig.6 shows the diagram of the detonator switch. The detonator is exploded and the explosion products make the aluminum ring form metallic jet and breakdown the insulation films between anode and negative electrodes, and then the storaged energy is discharged to the load.

Fig. 6. Diagram of detonator switch

Fig. 7 shows the photoes of two apparatuses and Table 1 gives the electrical parameters of these two apparatuses.

capacitor

354 Hydrodynamics – Advanced Topics

ceramics, steel or acryl glass. The base plate is used to confined the high pressure gas and plasma and reflect them to opposite direction to propel the flyers. The base plate also insulates the anode from the cathode transimission lines. So the material of base plate is

The whole working process is that the large current flows through the metallic foil instantly and the metallic foil goes through from solid, to liquid, gas and plasma, and then the high pressure gases and plasmas expand to some direction to drive the polyester Mylar flyer to

Based on low inductance technologies of pulsed storaged energy capacitor, detonator switch and parallel plate transmission lines with solid films insulation, two sets of experimental apparatuses with storaged energy of 14.4 kJ and 40 kJ were developed for launching hypervelocity flyer. The first apparatus is only consisted of one storaged energy pulsed capcitor with capacitance of 32 F, inductance of 30 nH and rated voltage of 30 kV. The parallel plate transmission lines and solid insulation films are used, which are with very low inducatnce. The thickness of insulation films is no more than 1 mm, which is composed of several or ten pieces of Mylar films with thichness of 0.1 mm. The second apparatus is composed of two capacitors with capacitance of 16 F and rated voltage of 50 kV in parallel. For two apparatuses, the detonator switch is used, which is with low inductance of about 7

Fig.6 shows the diagram of the detonator switch. The detonator is exploded and the explosion products make the aluminum ring form metallic jet and breakdown the insulation films between anode and negative electrodes, and then the storaged energy is discharged to

nH and easy to connected with the parallel plate transmission lines.

non-metal and the ceramics is a good one.

high velocity and impacts the targets.

Fig. 6. Diagram of detonator switch

the load.

(b)

Fig. 7. Experimental apparatuses of metallic foil electrically exploding driving flyers. The apparatus with energy of 14.4 kJ (a) and the apparatus with energy of 40 kJ(b).

Magnetohydrodynamics of Metallic Foil Electrical

velocities of the flyers (b)

Fig.9, Current *J*

compression

introduce some important applications of this tool.

**3.2 Magnetically driven quasi-isentropic compression** 

Explosion and Magnetically Driven Quasi-Isentropic Compression 357

(b)

As described above, the apparatus of metallic foil electrically exploding driving flyers is a good plane wave generator for shock wave physics experiments. In the last part, we will

The techinques to realize magnetically driven quasi-isentropic compression are based on all kinds of pulsed power generators, such as ZR, Veloce[29], Saturn[30] facilities. As shown in

Fig. 9. Experimental configuration of samples for magnetically driven quasi-isentropic

flowing at the anode and cathode surfaces induces a magnetic field *B*

 in

Fig. 8. The experimental results of the velocity of the flyer in different conditions. The velocities of the flyers vary from charging voltages (a) and the calculated and measured


Table 1. Parameter Values of our two apparatuses

Table 2 gives the performance parameters of our two apparatuses of metallic foil electrically exploding driving flyers.


Table 2. The performance parameters of our two apparatuses

The typical velocity histories of the flyers are shown in Fig.8, which are measured by laser interferometer, such as VISAR (velocity interferometer system for any reflectors)[27] or DISAR(all fibers displace interferometer system for any reflectors)[28].

1 32 30 14.4 14 40 7.1 7.5×<sup>1011</sup> Single

Table 2 gives the performance parameters of our two apparatuses of metallic foil electrically

Flyer—Mylar (6~20)mm×(0.1~0.2)mm (10~30)mm×(0.1~0.3)mm

Barrel—PMMA (6~20)mm×(4~15 )mm (10~30)mm×(4~15 )mm

25 ns 35 ns

The typical velocity histories of the flyers are shown in Fig.8, which are measured by laser interferometer, such as VISAR (velocity interferometer system for any reflectors)[27] or

(a)

/(A/s) Remarks

(10~30)mm×(10~30)mm×0.05

mm

capacitor

Two capacitors in parallel

setup *C*/F *U*0/kV *E*/kJ *R*/m *<sup>L</sup>*/nH *T*/s (d*I/*d*t*)t=0

2 32 50 40 10 36 6.75 8.4×1011

Parameters Setup 1 2

Flyer velocity 3~10km/s 3~15km/s

DISAR(all fibers displace interferometer system for any reflectors)[28].

Foil—Aluminum (6~20)mm×(6~20)mm×0.028 mm

Table 2. The performance parameters of our two apparatuses

Table 1. Parameter Values of our two apparatuses

exploding driving flyers.

Flyer Simultaneity at

Impact

Fig. 8. The experimental results of the velocity of the flyer in different conditions. The velocities of the flyers vary from charging voltages (a) and the calculated and measured velocities of the flyers (b)

As described above, the apparatus of metallic foil electrically exploding driving flyers is a good plane wave generator for shock wave physics experiments. In the last part, we will introduce some important applications of this tool.
