Shock Temperatures

In this chapter we define what is meant by a shock-wave equation of state, and how it is related to other types of equations of state. We also discuss the properties of shock-compressed matter on a microscopic scale, as well as discuss how shock-wave properties are measured. Shock data for standard materials are presented. The effects of phase changes are discussed, the measurements of shock temperatures, and sound velocities of shock materials are also described. We also describe the application of shock-compression data for porous media. 

It is useful to carry out both postshock and shock temperature measurements as they provide complementary information for the thermal equation of state, i.e., y, as well as Q. Using (4.55), (4.64), and (4.65), shock temperatures for materials such as MgO have been measured and these measurements compare favorably with the calculations (Fig. 4.27). 

Figure 4.25. Experimental configuration for optical pyrometry of shock temperatures induced in transparent minerals. Upon impact of projectile with driver plate, a shock wave is driven into the driver plate and then into the sample. Optical radiation from the sample is detected via six lens/interference filter channels and an array of six photodiodes. Signals from photodiode circuits are recorded on oscilloscopes operating in single sweep model. (After Ahrens et al. (1982).)...

Although there have been few data collected, postshock temperatures are very sensitive to the models which specify y and its volume dependence, in the case of the Gruneisen equation of state (Boslough, 1988 Raikes and Ahrens, 1979a Raikes and Ahrens, 1979b). In contrast, the absolute values of shock temperatures are sensitive to the phase transition energy Ejp of Eq. (4.55), whereas the slope of the versus pressure curve is sensitive to the specific heat (see, e.g.. Fig. 4.28). 

Figure 4.28. Measured and calculated shock temperatures versus pressure for for-sterite for low-pressure (olivine), mixed phase, and high-pressure phase regime (possibly MgO periclase) -I- MgSi03 (perovskite)). Shock temperatures in the mixed phase regime (Ahrens et al., 1969).

Figure 4.29. Sample assembly for optical shock temperature measurements. The sample consists of a metal film deposited on a transparent substrate which serves as both an anvil and a transparent window through which thermal radiation is emitted. Rapid compression of gases and surface irregularities at the interface between the sample film and the driver produce very high temperatures in this region. The bottom portion of the figure illustrates the thermal distribution across through the assembly. (After Bass et al. (1987).)...

Figure 4.31. A comparison of the results from shock temperature measurements on Fe. Hatchured area for Fe melting is defined by the results of Bass et al. (1987), Williams et al. (1987), and the theoretical calculations of McQueen et al. (1970) predict that the shock temperatures of solid stainless steel are lower than for pure, solid iron, as observed.

Using the parameters of Table 4.2, calculate the shock temperatures of MgO to 200 GPa and compare your results with those of Fig. 4.27. 

Boslough, M.B., and Ahrens, T.J. (1989), A Sensitive Time-Resolved Radiation Pyrometer for Shock-Temperature Measurements above 1500 K, Rev. Sci. Instrum. 60,3711-3716. 

Raikes, S.A., and Ahrens, T.J. (1979a), Measurements of Post-Shock Temperatures in Aluminum and Stainless Steel, in High Pressure Science and Technology (edited by Timmerhaus K.D. and M.S. Barber), Plenum, New York, pp. 889-894. 

Fig. 5.25. The shock temperature in LiCl KCl electrolytes is controlled with the use of eleetrolytes with initial densities as shown. The cirele represents the shock conditions. Upon release of pressure the final temperature is expected to cross the melt eurve for certain initial conditions.

Drilling surface data such as weight-on-bit and torque were difficult to interpret because they were loosely related to downhole values. MWD for the first time in the history of drilling gives values of parameters measured at the bit or close by. Rock strength, bit wear, drag and friction can be calculated in real time. Shocks, temperature and pressure can also be measured. 

Abravaya, K., Phillips, B., Morimoto, R.I. (1991a). Attenuation of the heat shock response in HeLa cells is mediated by the release of bound heat shock transcription factor and is modulated by changes in growth and in heat shock temperatures. Genes and Dev. 5, 2117-2127. 

The instrument MIMOS 11 is extremely miniaturized compared to standard laboratory Mossbauer spectrometers and is optimized for low power consumption and high detection efficiency (see Sect. 3.3) and [326, 327, 336-339]. All components were selected to withstand high acceleration forces and shocks, temperature variations over the Martian diurnal cycle, and cosmic ray irradiation. Mossbauer measurements can be done during day and night covering the whole diurnal temperature... 

There are no direct measurements of the degree of ionization of strongly shocked noble gases. Thus the validity of the above discussion can only be tested indirectly by comparing computed shock temperatures (which contain... 

At very high compression ratios, on the other hand, as p,/pu approaches a limiting or near-limiting value, the temperature climbs precipitously, as does the Mach number. It can be readily shown, by comparing the shock temperatures with those obtained in an adiabatic and isentropic compression T oc of comparable pressure change that there is much... 

---