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053512-6 Matsumoto et al.
Rev. Sci. Instrum. 87, 053512 (2016)
Langmuir probe measurement is a local measurement of the electron density around the tip of probe. The estimated particle inventory for a cylindrical CT with a 10 cm diameter is shown in Fig. 8(b). The particle content was estimated from ⇤ nedldV/L = ⇤ nedl⇡vzdt, where V is the volume and vz is the velocity of CT. To estimate the CT length, we have to decide truncation time. Accordingly, the CT length was estimated from Fig. 8(a) by the full width at half maximum (FWHM). From Fig. 8(b), the particle inventory is approximately ⇠6.4 ⇥ 1018. Then, the length of CT was estimated ⇠30 cm by vz ⇥ tfwhm, where tfwhm is time of FWHM from He-Ne laser interferometry.
IV. SUMMARY
We described a newly designed magnetized coaxial plasma gun for particle refueling of energetic FRCs. Our CT injector can be easily modified if di↵erent parameters are needed (e.g., velocity, flux, and particles): modification of acceleration region for ejection velocity and modification of interlinkage poloidal magnetic flux distribution for CT formation. The CTs produced by this MCPG have su cient parameters for penetration into C-2 external field, with velocities, electron density, electron temperature, particle inventory, and energy density of ⇠100 km/s, ⇠5 ⇥ 1021 m 3, ⇠40 eV, 0.5–1.0 ⇥ 1019, and 41.8 kJ/m3, respectively.
The resultant CT injector has already been deployed on the C-2 device and has successfully injected CTs into the
C-2 FRC.15 The particle inventory of typical C-2 FRCs was increased approximately 10%–20% by such CT injection and without disruption to the target plasma.
ACKNOWLEDGMENTS
This work is supported in part by the MOU as a part of research cooperation between the University of California at Irvine (School of Physical Science, Department of Physics and Astronomy) and Nihon University (College of Science and Technology, Department of Physics).
The authors would like to thank M. Nagata and N. Fukumoto, who are from University of Hyogo, for their technical assistance to design.
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