M. Hamagaki

M. Otsuka

T. "Ohgo

T. Hara

T." Kuroda

National Institute for Fusion Science (NIFS-Repository)

§ 14. Development and Application of I on Source Excited by a DC High-Current Electron Beam Ohgo, T. (Fukuoka Univ. of Edu.) Hara, T. (Toyota Technological Institute) Hamagaki, M. (RIKEN) Otsuka, M. (Honorary Prof. of Nagoya Univ.) Kuroda, T. A DC high-current electron beam gun has been investigated for development of new type ion source, which has optimum energy for ionizing inert gas atoms by collision. We report here on the measurement of electron density and temperature by the Thomson scattering with the YAG laser. The experimental setup has been shown in Ref.1. The scattering profiles reflect the distribution of the electron velocity perpendicular to the electron beam propagation. An example of the profile is shown in Fig.1, of which conditions are a helium gas pressure (P) of 0. 22 Torr, an acceleration voltage (Va) of 100V and an electron beam current (Ib) of 15A Each dot shows an average value of every 30 shots. A solid line indicates Maxwell distribution corresponding to the electron temperature of 2. 2 e V. All the profiles fit the Maxwellian except the case of P =6. 7 mTorr. In this case, the profile has several peaks symmetrically about the laser wavelength as shown in Fig. 2. This separation disagrees with the predicted value from the electron gyromagnetic frequency. Other discussions need to explain this structure of the spectrum, which is under investigation. The results are summarized in Table 1. This plasma source can produce a plasma which has wide range temperature of one order with the density of about 1014 cm-3. These parameters are difficult to be reached with usual plasma sources. Especially, in P=0.5 Torr the electron temperature is very low as 0. 6 e V with high electron density of -1014 cm-3. It is thought that the plasma of such parameters has advantage to produce negative ion because low temperature plasma with high density shows tendency to produce negative ion in the volume. 1)0hgo, T, et al. :Ann. Rep. NIFS (1993-1994) 100. 120 P=0.22 Torr Va=lOOV 7 6 ,.-.._5 > s '-"'4 >. +J ·en c 3 <l) · ·· · · ·,· ·· ·······('···· +J c ~ 2 ..... ~. . . ... -. j.. . . . 1 0 526 530 534 538 542 Wavelength (nm) Fig. 1. Typical example of the scattering profile and the Maxwellian distribution. P=6. 7 mTorr Va=lOOV 2 0.5 0'--___.l_____J_......L_____..L_--L..___L___:::..c___J 526 530 534 538 542 Wavelength (nm) Fig.2. Scattering profile at P=6. 7 mTorr. P(Torr) 6.7x10-3 0.22 0.5 Ib(A) 19 15 15 Va(V) 50 100 50 100 50 100 Te(eV) - 10 2 2.2 0.42 0.58 Ne(xlo13cm-3) - 3.2 9.6 8.6 7.2 8.9 Table 1. Electron densities and temperatures. 

Development and Application of Ion Source Excited by a DC High-Current Electron Beam

Abstract

Similar works

Full text

Available Versions

National Institute for Fusion Science (NIFS-Repository)