page_title: Wang Dezhao
section_title: Career in France
hierarchical_section_title: Wang Dezhao / Career in France
caption_attribution_description: English: Familles Ouang, Joliot-Curie et Biquard in 1941
context_page_description: Wang Dezhao or Ouang Te-Tchao was a Chinese physicist who was known for his research in atmospheric electricity and underwater acoustics. Under the direction of Paul Langevin, he helped the French improve sonar at the beginning of World War II and after his return to China, Wang was considered as the founder of national defense water acoustics in China.
context_section_description: Wang was entrusted by Langevin with the research on ionization of particles suspended in the atmosphere, a domain in which Langevin himself had abundantly researched at the turn of the 20th Century for his own doctoral thesis, and in which the world of scientists were increasingly interested for its utility in meteorology and radio-electronics. From 1934 to 1940, Wang published 9 scientific papers and completed the task with his French state doctoral thesis on the Electrization of the Particles Suspended in the gas. Langevin performed a complementary calculation on the results obtained by Wang on a roll of toilet paper when he was secretly imprisoned during 38 days by the Gestapo and then, he reviewed a part of Wang's thesis when he was under house arrest by the end of 1940. Wang's new discoveries on the equilibrium between big and small ions of suspended particles in the gases, as well as the equation he obtained between the numbers of big/small ions and the mobility of small ions, confirmed and completed later by another French scientist J. Bricard in 1948, was referred to as "Langevin-Ouang-Bricard" theory by the geophysical science community in the 1950s.
  In 1939, shortly after France and U.K. declared war against Nazi Germany, while all the Langevin laboratories at ESPCI was converted to the Research Group IV of the National Defense Ministry, Wang worked on multiplying the emission power of the ultrasonics submarine detector - known as Sonar today - that Langevin invented by the end of World War I using piezoelectric quartz crystals transducer. Wang succeeded to increase its power per unit area by applying sintering process, which improved greatly the efficiency and the reliability of the active sonar system. The technology was transferred to the UK Royal Navy for immediate implementation. Wang has also succeeded to put together an acoustic system capable of dispersing the heavy fog on military airports by creating large amplitude sound waves using a series of high air pressure Hartmann whistles causing the dispersal of particles suspended in the air.
  A profound friendship was built up between Ouang and Langevin beyond their student-teacher relationship. During the World War II, while Langevin was under home arrest, Wang refused to work for ESPCI led by a pro-German director Jean Thibaud and joined Irène and Frédéric Joliot-Curie - also student of Paul Langevin - at their Institute du Radium, where he researched more in radioactivity until the liberation of Paris by allied forces and the return of Langevin to ESPCI. From that point to the middle of 1950s, while continuing the research in ionized gases based on Langevin's theory and his previous work, Wang made breakthroughs in the following domains:
  Inventing high sensibility electrometers;
  Measuring the absorption, dispersion and speed of ultrasound in fluid;
  Proving the existence of negative electrophoresis discovered by Felix Ehrenhaft;
  Using β ray to measure and control the thickness of emulsion on photo film and paper.
  After the war, Wang was awarded with the Prix Hughes by the Academie des Sciences in 1945 for his contribution in the field of ionized gases; and was promoted by Centre national de la recherche scientifique (CNRS) from researcher to research director. In 1947, by the recommendation of Frédéric Joliot-Curie, he was appointed consultant to the Commisariat à l'Energie Atomique (CEA). He has also been working as scientific consultant for some private companies in France and in the U.K., la Société Quartz and Silice among others.
  Influenced by Langevin and Joliot-Curie, both French communist party members, as well as the communist dominant French Resistance movement during the german occupation of the WWII, Wang was also involved in the social life in Paris. In 1949 he was elected president of Association of Chinese students in France - a progressive association regrouping the left-wing Chinese students - disbanded in the fall 1952 by the French government under the global anti-communist waves and at the request of the Republic of China's government w
caption: Wang, Joliot-Curie and Biquard families in summer 1941
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