Goro Kamimoto

Destruction of basaltic bodies by high-velocity impact

As a simulation of collisional processes among solid bodies of various sizes in the solar system, polycarbonate projectiles of mass 0.37 g were impacted against cubic basaltic rocks of about 2 to 10 cm and larger with a velocity of 2.6 km/sec. The corresponding energy imparted per unit mass of target ranges from about 106 to 109 ergs/g. The phenomena are classified into four categories with increasing target size: (1) complete destruction, (2) remaining core, (3) transition region, and (4) crater formation. Empirical formulas for the cumulative mass of the fragments and the mass of the maximum fragment are given. The similarity of these formulas is briefly discussed. The experimental results are applied to the examination of the hypothesis that a single Martian satellite was once ruptured by impact, leaving the present two satellites. It is suggested that the radius of the parent satellite was larger than about 30 km.

Vibrational Relaxation of Nitric Oxide in Argon

Vibrational relaxation times of NO diluted in Ar were measured by monitoring infrared emission of NO at 5.3 μ. Measurements were made in shock waves over the temperature range of 900–2700°K. NO was found to relax exponentially and the relaxation times of NO in NO–NO and NO–Ar collisions were estimated. The results were expressed by logpτNO–NO = 6.1T−1/3 − 1.1 atm·μsec and logpτNO–Ar = 14.7T−1/3 + 0.15 atm·μsec.

Vibrational Relaxation of Carbon Dioxide in Argon

Vibrational relaxation of CO2(ν3) diluted in Ar was studied over the temperature range 700–2000°K by using a shock‐tube technique. Measurements were made by monitoring the infrared emission of the asymmetric stretching mode of CO2 at 4.3 μ. The relaxation profile of CO2(ν3) was found to be nonexponential by intramolecular V–V couplings with other modes and all the modes in CO2 had approximately the same final relaxation time τf on CO2–Ar collisions. The relaxation time for the V–V process between ν1,2 and ν3 modes was estimated by using a simplified two‐modes model.

Spectroscopic Measurements of Weakly Ionized Argon Plasma Jet

The properties of weakly ionized argon plasma flow premixed with N2 in the plenum chamber are studied by the spectroscopic technique.A preliminary study is made of the physical processes occuring in the plenum chamber, and it is demonstrated that three competitive reactions of ground state nitrogen molecule, free electron and ground state argon atom for metastable argon atom play an important role in the possible reactions.The rotational temperatures using the N2 2nd positive (0, 0) band are also measured taking account of the overlapping of P and R branches, and it is found that electron temperature is about twice as large as the rotational temperature.Such a measurement of the free stream in the test section is very difficult because of the lack of the knowledge of the excitation mechanism from X1Σ state of N2 to C3II by the metastable Ar atom.

New Hypersonic Gun Tunnel at Kyoto University

The many informations about the performances of the gun tunnel had been obtained theoretically and experimentally by the pilot gun tunnel which was constructed at Kyoto University in 1962. By these data, a large-sized hypersonic gun tunnel at Uji Campus in Kyoto University was new-built on March in 1967. In this paper, its mechanisms and performances are discussed. The peculiar mechanisms are adopted as follows; i) Double diaphragm type, ii) Automatic operating system, iii) Central control system, etc. The experimental results of the performances give the followings; i) Mach numbers of 9.515.6, ii) Duration time of 0.070.86 sec, iii) Stagnation temperature of 1, 0001, 300°K and so on.

The Behaviour of the Charged Particles Across a Shock Wave in a Partially Ionized Gas

The electron temperature and the ion density across the normal shock wave in the nonequilibrium, weakly ionized argon were measured by means of the LANGMUIR probe technique at Mach numbers of 4.17, 4.39 and 4.88. The electron temperature distribution across the shock in a nonequilibrium weakly ionized gas was calculated using the NAVIER-STOKES equation and it was found that the existence of the broad thermal layer of the elevated electron temperature was determined by Mach number and the degree of the nonequilibrium. Calculations were in fairly good agreement with experimental results, excepting the case where the degree of the nonequilibrium was great. Considering the decay of the free-stream ion density, the ion density distribution across the shock was calculated using the Morr-SMITHs solution for the neutral shock, and it was shown that the ion density decrease due to chemical reaction, diffusion, etc. in the free stream had great influence on it. These calculations agreed well with the experimental results, especially in the density ratio, and these agreements confirmed the above influence.

Velocity Measurement in Hypersonic Gun Tunnnel

Velocity of a free jet in hypersonic gun tunnel was measured by the probe method, and stagnation temperature was estimated considering the effects of vibrational excitation of molecules in air. Velocity distributions parallel and perpendicular to the jet axis, history during the operation of the tunnel, or effects of pressure ratio and Mach numbers were examined in detail. By tracking the growth of ionized clouds, the deflection angle of jet was also measured.

Caluculations and Experiments on Dissociated Carbondioxide by Shock Wave

Caluculations of the properties about dissociated carbondioxide in chemically equilibrium state can be simplified using the technique similar to the LIGHTHILLs one. If the temperature is not so high, (lower than 5, 000°K) these results agree well those caluculated by SIMCOX. From the one dimensional shock wave relations by means of these results, the equilibrium conditions behind the incident and reflected shock waves can be estimated. Experiments on the velocity of the reflected shock waves and the pressure behind the reflected shock waves suggest that the dissociation effects increase rapidly when shock Mach numbers are more then 8.