MCCARRICK Mi カリフォルニア大学, ロサンゼルス校・物理学科, 助手
WUERKER ralph f. HIPAS Observatory The University of California, Los Angeles Assoc.Dir., ロサンゼルス校・HIPAS Observatory, 副所長
WONG alfred y. Department of Physics The University of California, Los Angeles Prof., ロサンゼルス校・物理学科 HIPAS Observatory, 教授所長
NAKAMURA Yoshiharu The Institute of Space and Astronautical Science Assoc.Prof., 宇宙科学研究所, 助教授 (20013708)
SAKURAI Tohru School of Engineering Tokai University Prof., 工学部, 教授 (00004416)
MCCARRICK michael j. Department of Physics The University of California, Los Angeles Res.Assoc.
US-Japan joint ionospheric modification experimental campaigns were held twice during the 1993 Japanese academic year at the HIgh-Power Auroral Stimulation (HIPAS) Facility near Fairbanks, Alaska, U.S.A. Various diagnostic techniques were tested, and the method to efficiently coordinate them during ionospheric modification experiments were developed.
In ionospheric modification experiments, high-power ground-based HF transmitters are used to induce large-scale, as well as small-scale, changes in the ionosphere. Various important plasma phenomena, such as nonlinear wave phenomena and plasma heating effects, can thus be investigated. The absence of walls and the long confinement time make the ionospheric plasma distinctively unique and different from conventional laboratory plasmas.
Achievements from our HIPAS campaigns are summarized below.
1. Excitation of ELF and VLF waves
ELF and VLF waves are excited by modulating the polar electrojet current through the modification of plasma conductivities using the heating effect of powerful HF waves. Satellite, as well as ground-based, observations were carried out in order to detect ELF (proton cyclotron frequency range) and VLF (whistler wave frequency range) signals.
2. Riometer observations
A riometer system with an array of eight dipole antennas was set up in order to measure the height and extent of the HF heated region. This measurement is vital in locating the region which is the source of ELF and VLF waves. To our knowledge, this is the first riometer measurement conducted in conjunction with ionospheric modification experiments. HF Doppler measurements were also performed using a low-power HF wave, whose frequency is slightly different from that of the heater HF wave, as a test wave.
3. New diagnostic techniques, such as HF phased-array radar and HF lidar systems, were tested.