Hybrid model for the calculation of ion distribution functions behind a direct current or radio frequency driven plasma boundary sheath

2001 ◽  
Vol 90 (5) ◽  
pp. 2169-2179 ◽  
Author(s):  
Matthias Kratzer ◽  
Ralf Peter Brinkmann ◽  
Winfried Sabisch ◽  
Harald Schmidt
Keyword(s):  
Radio Frequency ◽  
Hybrid Model ◽  
Direct Current ◽  
Plasma Boundary ◽  
Distribution Functions ◽  
Ion Distribution

A New Automatic Demultiplexing Method for NRZ-OOK Polarization-Division Multiplexed System

2011 ◽  
Vol 204-210 ◽  
pp. 1636-1639
Author(s):  
Qi Jing ◽  
Yong Qing Huang ◽  
Yang An Zhang ◽  
Ming Lun Zhang ◽  
Li Dong Mei
Keyword(s):  
Radio Frequency ◽  
Direct Current ◽  
Beam Splitter ◽  
System Simulation ◽  
Polarization Controller ◽  
Polarization Beam Splitter ◽  
Optical Polarization ◽  
Control Signals ◽  
Detection Window

A new automatic optical polarization demultiplexing method for NRZ-OOK polarization division multiplexed (PDM) system is proposed. The detected power differences of both the direct current (DC) and the radio frequency (RF) are used as control signals which are sensitive to the angles between the polarization controller (PC) and the polarization beam splitter (PBS). The characteristics of those control signals are thoroughly analyzed, and the best RF detection window is calculated out through system simulation.

The hot hELicon eXperiment (HELIX) and the large experiment on instabilities and anisotropy (LEIA)

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
E. E. Scime ◽  
P. A. Keiter ◽  
M. M. Balkey ◽  
J. L. Kline ◽  
X. Sun ◽  
...  
Keyword(s):  
Double Layer ◽  
Noble Gas ◽  
Velocity Distribution Function ◽  
Plasma Source ◽  
Distribution Functions ◽  
Double Layers ◽  
Driving Frequency ◽  
Ion Temperature ◽  
Temperature Anisotropy ◽  
Ion Distribution

The West Virginia University Hot hELIcon eXperiment (HELIX) provides variable density and ion temperature plasmas, with controllable levels of thermal anisotropy, for space relevant laboratory experiments in the Large Experiment on Instabilities and Anisotropy (LEIA) as well as fundamental studies of helicon source physics in HELIX. Through auxiliary ion heating, the ion temperature anisotropy (T⊥/T∥) is variable from 1 to 20 for parallel plasma beta (β = 8πnkTi∥/B2) values that span the range of 0.0001 to 0.01 in LEIA. The ion velocity distribution function is measured throughout the discharge volume in steady-state and pulsed plasmas with laser induced fluorescence (LIF). The wavelengths of very short wavelength electrostatic fluctuations are measured with a coherent microwave scattering system. Operating at low neutral pressures triggers spontaneous formation of a current-free electric double layer. Ion acceleration through the double layer is detected through LIF. LIF-based velocity space tomography of the accelerated beam provides a two-dimensional mapping of the bulk and beam ion distribution functions. The driving frequency for the m = 1 helical antenna is continuously variable from 8.5 to 16 MHz and frequency dependent variations of the RF coupling to the plasma allow the spontaneously appearing double layers to be turned on and off without modifying the plasma collisionality or magnetic field geometry. Single and multi-species plasmas are created with argon, helium, nitrogen, krypton, and xenon. The noble gas plasmas have steep neutral density gradients, with ionization levels reaching 100% in the core of the plasma source. The large plasma density in the source enables the study of Aflvén waves in the HELIX device.

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