**5.2 Magnetically driven quasi-isentropic compression 5.2.1 Compression isentropes of copper and aluminum**

The experimental compression isentropes of T1 copper andL1 pure aluminum(Al content more than 99.7%) were measured on the CQ-1.5. The free-surface velocities were measured by DISAR, and the data were processed with the backward integration code developed by us. For the design of sample sizes, it is necessary that shock should not be formed in the samples and the side rarefaction wave should not affect the center regime to meet the requirements of one dimensional strain loading. Table 5 are the sizes of experimental samples.


Table 5. Experimental conditions

Equation of state (EOS) measurement is an important potential application for our apparatus. In order to increase the loading pressure of this apparatus, two improvements should be done. Firstly, the flyer should be Mylar-metal foil laminate flyer . The metal layer

Secondly, the storaged energy of apparatus should be increased. The expected pressure

Impact experiment on the structure is also an important application for the apparatus of metallic foil electrically exploding driving high velocity flyer. For the apparatus of metallic foil electrically exploding driving high velocity flyer, its environment is well-controlled and instrumented, so it is suitable for studying impact phenomena in the fields of space science.

The experimental compression isentropes of T1 copper andL1 pure aluminum(Al content more than 99.7%) were measured on the CQ-1.5. The free-surface velocities were measured by DISAR, and the data were processed with the backward integration code developed by us. For the design of sample sizes, it is necessary that shock should not be formed in the samples and the side rarefaction wave should not affect the center regime to meet the requirements of one

Fig.27 shows a result of flyer of our apparatus impacting multi-layer structure.

Fig. 27. Experimental result of flyer impact multi-layer structure

dimensional strain loading. Table 5 are the sizes of experimental samples.

**5.2 Magnetically driven quasi-isentropic compression 5.2.1 Compression isentropes of copper and aluminum** 

Table 5. Experimental conditions

s shock impedance and thus the pressure produced in the target.

**5.1.3 Potential applications** 

should be up to 200 GPa or more.

increases the flyer'

Fig.28(a) are the typical free-surface velocity histories measured by DISAR, which show that the slope become steeper for thicker sample. The experimental compression isentropes, theoretical compression isentropes and shock Hugoniots data are presented in Fig.28(b) and Fig.28 (c).

Fig. 28. Results of ICEs.(a) typical histories of free-surface velocity. (b) experimental, theoretical isentropes and Hugoniots data of T1 copper. (c) experimental isentrope of L1 pure aluminum, isentrope ang Hugoniot data of 6061-T6 aluminum from reference [39].

The results show that the experimental compression isentropes are consistent with the theoretical ones within a deviation of 3%, and are close to the shock Hugoniot data under the pressure of 40GPa and lies under them. Different from the shock method, the whole isentrope can be obtained in one shot, and tens of shots are needed to gain one shock Hugoniot curve. The calculation results[40] show that the compression isentropes gradually deviate from the shock Hugoniots with the increasement of loading pressure over 50 GPa. Therefore, the compression isentropes mainly reflect the off- Hugoniot properties of materials. Under 50 GPa, the compression isentropes are close to the shock Hugoniots, so we can use the isentrope data to check the validity or precision of shock Hugoniots.

Magnetohydrodynamics of Metallic Foil Electrical

Fig. 30. Velocity profiles of Tantalum samples

steel and from 1.12 to 1.25 GPa for pure tantalum.

**5.2.4 Magnetically driven high-velocity flyers** 

results of the velocities of the flyers.

Explosion and Magnetically Driven Quasi-Isentropic Compression 375

at the loading strain rate of 2.53×105 1/s. Because of the difference of loading strain rates, the

It is an important application to launch high-velocity flyer plates using the techniques of magnetically driven quasi-isentropic compression. For the present, the reseachers has launched the aluminum flyer plate with the size of 15 mm×11 mm×0.9 mm to the velocity of 43 km/s using this technique[23], and can produce 1~2 TPa shock pressure on the heavy metallic or quartz samples. Based on CQ-1.5, the aluminum flyer plate with the size of 8 mm×6 mm×0.9 mm was launched to about 9 km/s by us. Figure 31 shows the experimental

(a) (b)

Fig. 31. The velocities of the aluminum flyer plates driven by magnetic ressure.The velocities measured by VISAR (a) and the averaged velocity measured by optical fibres pins (b)

IEL ranges from 2.26 to 2.35 GPa for 45 steel, and from 2.42 to 2.70 GPa for pure tantalum in our experiments, correspondingly, the yield strength ranges from 1.29 to 1.34 GPa for 45
