No abstract

The use of magnetic material can improve the performance of a single-flux-quantum device by inducing high self-or mutual inductance, which can reduce the size or increase the sensitivity of the device. We used magnetic nanoparticles as the magnetic material and adopted photoresist patterns with Fe 3 O 4 nanoparticles as a means of inserting nanoparticles into a device. The effect of the nanoparticles was investigated for SQUIDs with photoresist patterns. Analytical estimation of the effect indicated a variation in SQUID inductance of less than 1%, which is in agreement with the experimental results in the absence of external magnetic fields. On the other hand, when external DC magnetic fields were applied, a slight increase in inductance was observed for several SQUIDs.

We evaluated the effects of Fe3O4 magnetic nanoparticle (NP) films on the electrical characteristics of superconducting quantum interference devices (SQUIDs) at 4.2 K to enhance the performance of superconducting circuits. The NP films were formed directly on the SQUIDs. For SQUIDs with 5-nm-NP films, the SQUID inductance increased almost linearly with the NP film thickness, reaching 19.7% at an NP film thickness of 990 nm. An increase in NP size from 5 to 20 nm reduced that in the SQUID inductance. On the other hand, no clear effects on the current–voltage characteristics of SQUIDs were observed for 5- and 10-nm-NP films, while the critical currents of some SQUIDs with 20-nm-NP films were reduced.

Abstract. Radiation emitted from the shock layer generated around a hypersonic flight model is experimentally investigated by using a ballistic range (two-stage light-gas gun). A polyethylene projectile of 1.2 cm in diameter is launched in this facility at the velocity of 5 km/sec (M = 15), and the emission from the induced shock layer around the projectile is observed with a spectroscope,. As a result, molecular band-spectra from NO and N2 are detected along with those from carboncontaining molecules. Total emission power is measured with a diode-type powerrneter. In addition, dimension effect of the flight model is theoretically and numerically examined, and a scaling law on thermochemical structure of the shock layer is developed. It shows that the thickness of thermal boundarylayer formed on the model surface does not follow the conventional scaling law based on the reaction distance and on the energy relaxation distance. Finally, the radiative field around the projectile is numerically computed, and the total power emitted from the shock layer is estimated. From the comparison between computed and measured results, the validity of the calculation model is discussed.

No abstract