We report on a localized high-density electron beam in large-area microwave discharges in argon. The beam is observed only for certain antenna configurations at gas pressures of about 50 mTorr, and it strongly modifies the radial plasma density profiles. The beam current near the quartz plate is estimated to be ≈140 mA/cm2.
The electron energy distribution functions are studied in low-pressure microwave surface-wave sustained plasma using retarding field analyzer. Sustained discharge can be considered as superposition of the bulk plasma and the high-energy electron beamlike part. The beam component energy is pronounced up to 40eV. Beam population reaches the maximum at energy of 16eV with amount of 4% of the bulk plasma population.
We report on the theoretical calculations of the effect of the polarization gradient and an axial magnetic field on quantum noise reduction and quantum jumps in the resonance fluorescence emitted by cold metastable helium atoms confined in an optical lattice. We find that the localization of the atoms in the optical lattice destroys the non-classical properties of the emitted light but can be recovered in the presence of an axial magnetic field. The polarization gradient induces electron shelving at selected points (z = nλ/4) on the optical lattice. At these selected points, squeezing is maximized.
The influence of a quartz side wall on plasma production was studied in a large-area surface wave plasma source. An enhanced plasma production was observed in the vicinity of the quartz side wall and is explained by the propagation of the surface wave coupled from the bottom quartz plate to the quartz side wall. This was confirmed by measuring the electromagnetic field intensity and the wavelength of the surface wave propagating along the side wall. Additionally, the plasma density was obtained by two different methods, that is, calculation using the dispersion relation and measurement using a Langmuir probe. It was found that the surface wave propagates along the quartz side wall in the direction perpendicular to the slot antenna axis, resulting in plasma production. As a consequence, the radial plasma density becomes more uniform in the region with the quartz side wall than in the region with a metal side wall.
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