High Temperature Gas Dynamics and Laser Diagnostics Group
Department of Mechanical Engineering, Shizuoka University / 静岡大学工学部機械工学科 松井研究室


Laser Sustained Plasma and its Application

1) Generation of Laser Sustained Plasma by High Power Diode Laser
 Laser-sustained plasma (LSP) is a promising method for stationary thermal plasma generation, which has advantages of clean flows without extremely low contamination, availability of active gases and higher pressure operation than atmosphere. However, the LSP has hardly been applied to industries because a kilowatt class high-power laser for LSP generation was formerly limited to CO2 laser, which is high initial and running cost, difficult maintenance due to the gas laser, low wall-plug efficiency (10 %), large size, a non-visible beam, and toxic non-clear Zn-Se optics due to its infrared wavelength. A diode laser has advantages of energy coefficient more than 50 % and installation cost. In this study, generating conditions of LSP by the diode laser is exmined.

2) Launch System by Laser Propulsion
 Today's launch vehicles produce energy by burning a propellant, which accounts for nearly 90% of the total weight. Laser propulsion is a space transportation system that obtains thrust with a laser beam transmitted from the ground as an energy source. By separating the energy source from the rocket, a significant cost reduction of the rocket can be expected. In addition to the feasibility study by numerical calculation, an experimental demonstrative test would be scheduled.

3) Alumina Reduction by Laser Sustained Plasma for Energy Cycling System
 Aluminum can store energy as a chemical potential which is a few orders of magnitude higher than that of Li-ion batteries or hydrogen, and almost equals that of fossil fuels. This allows storing the renewable energy in aluminum on a suitable site and transporting it to a consuming region, where electricity is extracted by a thermal power plant. A key technology in the cycling process is the reduction of alumina. In this study, we employed LSP to reduce alumina by thermal dissociation, which is a zero-emission method different from the conventional Hall-Heroult process.

Development of Laser Diagnostics Methods for Flow Evaluation

 We have been developing following non-intrusive diagnostics methods based on laser spectroscopy to characterize flow and plasma properties.
-Wavelength modulation and integrated cavity output spectroscopy for AO density measurement
-High speed wavelength modulation spectroscopy for temperature measurement
-Laser induced fluorescence for electric field measurement
-Mach-Zehnder interferometer for electron density measurement


Generation Process of Sono-luminescence

 Sonoluminescence (SL) is a light emission phenomenon that occurs when bubble nuclei in a liquid expand and crush in synchronization with applied ultrasonic waves. It is reported that  SL is a plasma state of several thousand atmospheres and tens of thousands of degrees. Although SL can create ultra-high pressure and temperature conditions with only a few hundred watts, its light emission time is as short as 1 ns (= 10 -9 s). So its physical process is not enough to be known. In this study, we aim to elucidate SL phenomena with ps-order (= 10-12 s) time resolution by using laser spectroscopy and streak camera.

Cooperative Graduate School with JAXA (連携大学院)

 Shizuoka University has a cooperative graduate school with JAXA. Our group collabrate following two groups; Dr. Okawa at Chofu Aerospace Center (CAC) and Prof. K. Fujita, Prof. I. Funaki and Associate Prof. K. Yamada at Institute of Space and Astronautical Science (ISAS)

1) Evaluation of pre-cursor Ionization in Shock Tube Flows (CAC/JAXA)
 A sample return mission from Jupiter Trojans currently is under consideration in JAXA. In this mission, the reentry speed to the atmosphere is predicted to reach as high as 15 km/s. The purpose of this research is to elucidate the shock wave structure and predict the radiant heating rate using a shock tube.
 衝撃波管を用いた衝撃波前方プリカーサー現象の解明 (調布航空宇宙センター/JAXA)

2) Evaluation of Expansion Tube Flows by Laser Diagnostics (ISAS/JAXA)
 An expansion tub is a unique device to produce high speed flows without stagnation conditions. Then, the flow is much closer to the actual one than those in shock tunnels and plasma wind tunnel. However, the operation time is as short as μs and the flow characteristics have not been sufficiently understood. Our group aims to establish laser diagnostics methods using an expansion tube at ISAS/JAXA and to characterize HEK-X flow conditions at the Kakuda Space Center.
 レーザー分光法による膨張波管気流評価 (宇宙科学研究所/JAXA)

3) Hall Thruster (CAS, ISAS/JAXA)
 Hall thrusters are currently widely used as thrusters for satellites and space probes because they have an order of magnitude greater thrust density than that of ion engines. JAXA is developing carbon dioxide propellants to replace expensive xenon propellants and high-power cathodes for future large Hall thrusters.
 ホールスラスタの開発 (調布宇宙センター、宇宙科学研究所/JAXA)

       100W class Hall thruster


TEL: 053-478-1064(教員室)
TEL: 053-478-1078(学生室)

3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan