Akira Hasegawa
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University of California, Berkeley (Ph.D.)
Nagoya University (Sc.D.)
- Hasegawa–Mima equation
- Hasegawa–Wakatani equation
- Kinetic Alfvén wave
- Levitated dipole
Akira Hasegawa | |
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長谷川晃 | |
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| Born | 17 June 1934 Tokyo, Japan |
| Died | 22 June 2025 (aged 91) |
| Education | University of Osaka (B.E., M.E.) University of California, Berkeley (Ph.D.) Nagoya University (Sc.D.) |
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| Scientific career | |
| Fields | Plasma physics, Optical solitons |
| Institutions | Bell Labs University of Osaka Nagoya University Columbia University École Polytechnique Fédérale de Lausanne |
| Thesis | Plasma Computer Simulation Using Sheet Current Model (1964) |
| Doctoral advisor | Charles K. Birdsall |
Akira Hasegawa (Japanese: 長谷川 晃, Hepburn: Hasegawa Akira; 17 June 1934 – 22 June 2025) was a Japanese theoretical physicist and engineer who worked in the U.S. and Japan. He is known for his work in the derivation of the Hasegawa–Mima equation,[1] which describes fundamental plasma turbulence and the consequent generation of zonal flow that controls plasma diffusion. Hasegawa also made the discovery of optical solitons[2] in glass fibers, a concept that is essential for high speed optical communications.
Hasegawa was the first to suggest the existence of optical solitons in 1973. In 1974, he (together with Liu Chen) showed that plasmas could be heated with the kinetic Alfvén wave.[3] Hasegawa and Chen introduced the concept of the kinetic Alfven wave to illustrate the microscopic process of the Alfven wave heating.[4] In 1977, Hasegawa introduced the Hasegawa–Mima equation to describe turbulence in Tokamak plasmas and then further developed it in the 1980s (with Masahiro Wakatani) to obtain the Hasegawa–Wakatani equation.[5] The equation predicted an inverse cascade in the turbulent energy spectrum (i.e., from small to large wavelengths) and zonal flows (in the azimuthal direction in the Tokamak) that can control radial turbulent diffusion.[6] With Wakatani, he wrote a paper on self-organized turbulence in plasmas.[7]
Hasegawa's proposal to trap plasmas with a dipole magnet similar to Earth's magnetic field, where turbulence caused by solar wind stabilizes the trap, was implemented in the first dipole plasma experiment[8] at University of Tokyo by Prof. Zensho Yoshida. In 2010, a plasma experiment with a floating dipole was also built at the Massachusetts Institute of Technology.[9]
Hasegawa was born on 17 June 1934, in Tokyo Prefecture.[10] He was a graduate of the Department of Communications Engineering at the University of Osaka, Japan and was a Fulbright student at the University of California, Berkeley, where he completed his Ph.D. under the supervision of Charles K. Birdsall in 1964. The title of his dissertation was Plasma Computer Simulation Using Sheet Current Model.
He subsequently took a post doctoral position at Bell Laboratories for six months, where he worked with Solomon J. Buchsbaum. Hasegawa was an associate professor in the Faculty of Engineering Science of the University of Osaka from 1964 to 1968. During this period, he served as a visiting professor at the Institute of Plasma Physics at Nagoya University and received the Doctor of Science Degree from the Department of Physics at Nagoya University.
Hasegawa rejoined Bell Laboratories in 1968, where he stayed as a distinguished member of technical staff until 1991. During his time at Bell Laboratories, he also became an adjunct professor in the Department of Applied Physics at Columbia University from 1971. He was a Distinguished Visiting Professor at the École Polytechnique Fédérale de Lausanne in 1980 as well as a visiting professor at the Institute of Laser Engineering at Osaka University. Hasegawa was elected as Chairman of the Division of Plasma Physics of the American Physical Society in 1990, when he reported to the President the importance of fusion research based on advanced fuels to avoid undesirable consequences of deuterium tritium fusion. In 1991, he resigned from Bell Laboratories and transferred to the Faculty of Engineering at Osaka University. He retired in 1998.
In addition to over 250 scientific papers and several text books, Hasegawa published a number of books on the subjects of Japanese and Zen culture, which he learned from his spiritual teacher, Kobori Nanrei Sohaku of the Daitoku-ji temple. Following his retirement from Osaka University, he took a position as a lecturer at Kobe Women's University to teach a course on Happiness for Japanese Women, upon request of the founder of the university, Mrs. Kaname Yukiyoshi. He also worked as a professor at Himeji Dokkyo University and Kochi University of Technology and was a special consultant with NTT Japan and BTG International.
Akira Hasegawa was born to Japanese parents who were divorced when he was very young. He was primarily raised by his mother, Kaoru Takata, who was a graduate of Science and Mathematics Department in Nara Women's University His mother was a strong influence in developing his interest in mathematics. Hasegawa played on a baseball team while at Nagasaka Junior High School. At Itami High School he was a member of the Science Club. While at Osaka University, he also played trombone in a Dixieland Jazz Band, which he and his friend formed. He spent all of his scholarship money to purchase a large collection of jazz records, extending from Bix Beiderbecke to Miles Davis.
In March 1961, prior to moving to the United States, Hasegawa was married to Miyoko. Together, they have two sons, Tomohiro and Atsushi, and a daughter, Akiko. He played tennis but mostly enjoyed playing golf. Akira enjoyed being a member of the Rotary Club of Kyoto-East and publishing books on various non-science themes including history, finance, and culture. He believed that Japan is a country established on a unique matriarchal culture during the Jomon period, some ten thousands of years BC.
In addition to an extensive academic publication record and the editorship and authorship of numerous scientific research level text books,[11][12][13][14][15][16][17][18][19] Hasegawa was prolific in the publication of various aspects of culture and philosophy in the past few years, writing on diverse topics such as life and entropy, the economy and finance, Lao Tzu and Confucius, as well as Japanese culture and religion. Many of the texts are available electronically in Japanese, as well as in English and include such titles as: "A Story of Life and Health",[20] "A Story of Money",[21] "Fund Management for those near Retirement",[22] "Method of Investments for Private Pension",[23] "The One World of Lao Tzu and Modern Physics: A Dialogue with a Zen Abbot",[24] "Mai and Dance and Japanese Culture",[25] "Enjoying Wine",[26] "Science and Religion",[27] "How to Increase Productivity in Service Industries",[28] "Japanese Women Changing the World".[29]
Hasegawa died on 22 June 2025, at the age of 91.[30]
