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Physics and Astronomy

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Departmental Colloquium

Laboratory Astrophysics at Tokyo Metropolitan University  
Guest Speaker
Prof. Hajime Tanuma  
Guest Affiliation
Department of Physics, Tokyo Metropolitan University  
Prof. Phillip Stancil  
Thursday, March 23, 2017 3:30 pm - 4:30 pm  
CSP Conference Room (322)  

At Tokyo Metropolitan University, three distinct experimental techniques are being deployed to study ionic and molecular processes relevant to astrophysics.

A facility for multiply charged ion beam experiments with a 14.25 GHz electron cyclotron resonance ion source is used to measure charge exchange cross sections in collisions of multiply charged ions with neutral gases and to observe photon emission spectra under soft X-ray, extreme ultraviolet, and UV-visible irradiation. Currently we are interested in both solar wind charge exchange phenomena and spectroscopic data needed for the fusion reactor ITER.

Our electrostatic ion storage ring, which was constructed in 2004 as the world’s third such device, is a facility that has become popular among atomic and molecular physicists. Using this ring, we have studied cooling processes of hot (around 3000 K) molecular and cluster ions, produced in an ion source. We have also performed experiments for C6H-, which is found in interstellar clouds, and small carbon anions.

In a low temperature ion drift tube mass spectrometer, which can be operated at 4.3 K by using liquid helium, the mobility of atomic and small molecular ions in helium gas has been measured and the formation of helium cluster ions has been observed. We have observed elastic cross sections between molecular ions and He larger than the Langevin limit at very low energies. This phenomena might contribute to chemical evolution in interstellar clouds.