We have demonstrated frequency up-conversion in the terahertz (THz) region by flash ionization, which occurs due a terahertz wave interacting with a plasma created by an ultrashort laser pulse. The upshift frequency is controlled by the plasma density. We performed a proof-of-principle experiment with a plasma creation time scale much shorter than the period of the electromagnetic wave and a plasma length longer than its wavelength. We upshifted the frequency from 0.35 to 3.5 THz by irradiating a ZnSe crystal with a Ti:sapphire laser pulse.

The MEE (More Electric Engine) is a concept for engine system electrification and is an evolutionary step in engine system design that contributes to the reduction of aviation CO2 emissions. Mifee (Metering and integrated fuel feeding electrification) and the E3M (Engine Embedded Electric Machine) are the key technologies of the MEE. The purpose of engine thermal management is maintaining the balance between heat generation by the engine system and heat dissipation to the outside of the engine. In recent engine system designs, thermal system design has become an issue because of increased heat generation within the system. For example, a recently developed turbo-fan engine system increases the heat generation by introduction of a fan drive gear system that produces a large amount of heat in addition to the conventional heat source, such as engine main bearings and gears. The MEE will have further heat sources within its system, like the E3M, which is a high-power electric machine. In this paper, an investigation approach and the result of a feasibility study of the MEE thermal management system is described. In addition, the perspective of the technology trend from the MEE toward future hybrid propulsion is also discussed. The global requirements for climate protection strongly demand game-changing technology that significantly improves the aircraft’s overall efficiency. A series/parallel partial hybrid propulsion system, in which both a turbo-fan engine and electrical motor-driven fans generate propulsive power, is considered to be one of the most promising approaches for the future commercial aircraft hybrid propulsion system. The MEE and E3M technology evolves until it will be applied in hybrid propulsion system.

Abstract. We demonstrate a frequency-tuning scheme that uses laser pulse duration to control the ultrafastdischarge current timescale. We also propose a simple physical model to explain the generation of terahertz radiation by laser propagation in an ultrafast-discharge.

We have demonstrated the proof of principle experiment using the interaction between a terahertz wave and plasmas created by an ultra short laser pulse, which ensures the plasma creation time-scale much shorter than a period of electromagnetic source wave and plasma length longer than a wavelength of the wave. We observed frequency up-conversion from 0.35 THz to 3.3 THz by the irradiance of the Ti:S laser in ZnSe crystal.

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