Tadao Honzawa

Control of Electron Temperature of a Plasma in Double Plasma Device

A method is described for varying the electron temperature of a plasma (target-plasma) in a double plasma device from 0.05 to 1.3 eV by adjusting the thermionic emission of electrons from filaments used in the region.

Ionization of Energetic Neutral Atoms on a Metallic Surface

Experimental study is described of the ionization of energetic neutral atoms on an untreated, metallic surface. The energy loss associated with the ionization is found to depend strongly on the incident angle of the particles onto the surface. The efficiency of ionization is of the order of 10 -6 . Angular distribution of the ions leaving the surface is also measured.

Controlled excitation and dispersion relations of nonlinear multimode waves in ion-beam-plasma system

Controlled excitation of nonlinear multimode waves, including slow and fast ion-beam modes as well as an ion-acoustic mode, has been realized in a linearly stable ion-beam-plasma system. The mechanism for the coexcitation of two unlike waves observed in the system is also clarified. Furthermore, nonlinear dispersion relations of the beam modes are experimentally determined from the amplitude dependences of the wave velocities and widths. The results are compared with the theoretical ones.

A Back-Diffusion Type Source of Monoenergetic Ions

The results of our experimental study on a back-diffusion type ion source, which can be operated in any kind of gas at a pressure from 10 -6 to 10 -3 Torr, are described. The source produces monoenergetic ions with a controllable kinetic energy from a few tens to several hundreds eV and density up to several times 10 7 cm -3 . The monoenergetic ions are neutralized by thermal electrons emitted from cathodes and hardly diverge during their run. They are available for the calibration of energy analyzers, experiments on collision processes of ions with atoms and so forth.

Loss Mechanism of Electrons from a Magnetic Bottle

The motion of electrons in a static magnetic field of mirror geometry was investigated by injecting a beam of KeV electrons with a small electron gun in the central region of the magnetic bottle. The first order orbit theory was well verified by high vacuum experiment. The The mirror loss of KeV electrons was studied by filling the vaccum chamber with helium and argon gases. The mean lifetime of trapped electrons was measured by making use of the azimuthal drift of electrons as a function of gas pressure. The elastic scattering of single or plural type is concluded to be the most responsible for the mirror loss at pressure of 10 -4 mmHg or higher.

A Modified PIG-Type plasmna Source

The experimental study is described of a plasma source of modified PIG-type. The source is operated in a magnetic field of moderate intensity, which changes seriously the motion of the electron component of plasma, but does not change so much that of the ion component. Since the usual plasma region of the source for various applications is separated by a grounded metallic mesh grid from the discharge region, fairly noiseless plasmas can be obtained with the source under a suitable condition in spite of the operation in a magnetic field. In addition, it is noted that for these plasmas the ion-temperature is several, times higher than the electron-temperature and somewhat controllable, and that there are contained neither electronic nor ionic beams.

Motion of Electrons in a Magnetic Bottle, II

In order to investigate the motion of electrons as single particles, we have constructed a magnetic bottle, into which electrons are injected by an electron gun, The magnetic bottle field was produced by a pair of air core coils excited by a steady current, A cylindrical vacuum chamber was inserted through the coils, so that its axis coincides with the magnetic axis, Electrons were injected at the center of the bottle and were observed at various positions.The present paper is the first report of our experiment, by which we aim at understanding qualitative features of the motion of electrons in our device, We are here interested mainly in the effect of scattering by gases on the mirror loss, In order to avoid the shadow effect of the gun as far as possible, electrons were injected as short pulses, so that a fraction of electrons getting rid of colliding with the gun system could be distinguished from those which have collided, The shadow effect was further eliminated by varying the pressure of a gas (He or A) filled in the chamber, The trapping time of injected electrons was deduced essentially from the intensity of slow electrons produced by their collisions with gas atoms and it was found to be accounted for in terms of the single Coulomb scattering. The lifetime of the slow electrons can be qualitatively explained by their atomic scattering.