Experimental Investigation of a Low Frequency Instability in a Modified Penning Discharge (Q-PIG)

1970 ◽  
Vol 25 (2) ◽  
pp. 263-273
Author(s):  
F . Klan
Keyword(s):  
Magnetic Field ◽  
Experimental Investigation ◽  
Electron Gas ◽  
Low Frequency ◽  
Frequency Instability ◽  
Qualitative Explanation ◽  
Low Frequency Oscillations ◽  
Low Frequency Instability ◽  
Low Magnetic Field ◽  
Detailed Picture

Abstract Low frequency oscillations observed in a modified PIG discharge were identified as fluctuations of the electron temperature. These oscillations only occurred under certain conditions (low gas pressure, relatively high magnetic field), whereas at high pressure and low magnetic field strength the plasma was remarkably stable; this is why the discharge is referred to as a "quiescent" PIG (Q-PIG) discharge. This paper describes measurements for obtaining a detailed picture of the two modes of the discharge. A qualitative explanation of the phenomena observed is obtained using the energy balance of the electron gas.

Purely growing electromagnetic modes in high-β plasmas

1974 ◽  
Vol 11 (3) ◽  
pp. 461-470 ◽  
Author(s):  
G. S. Lakhina ◽  
B. Buti ◽  
Girija Nayar
Keyword(s):  
Magnetic Field ◽  
Growth Rates ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Frequency Instability ◽  
Wave Number ◽  
Unstable Wave ◽  
Distribution Index ◽  
Kinetic Pressure ◽  
Low Frequency Instability

Electromagnetic waves propagating transverse to an external magnetic field in a high-β (β being the ratio of the kinetic pressure to the magnetic pressure) plasma become unstable through purely growing modes when β∥e, (electron β parallel to the magnetic field) exceeds a certain minimum value β∥*. For J ≦ 2 (J being the distribution index), the region of instability consists of a single band of unstable wavenumbers k, whereas for J ≥ 3 more than one unstable wave number band may exist. The growth rates are largest for J = 0, and tend to decrease as J increases. The presence of hot ions increases the instability region by exciting a low-frequency instability. This instability gets excited at considerably lowered values of β‖e, and has growth rates of the order of ion cyclotron frequency. The effect of T‖i/T‖e and T‖e/T⊥e is destabilizing, whereas that of T⊥i/T⊥e is stabilizing.

scholarly journals TRANSPORT PROPERTIES OF 2D ELECTRON GAS IN AN n-InGaAs/GaAs DQW IN A VICINITY OF LOW MAGNETIC-FIELD-INDUCED HALL INSULATOR–QUANTUM HALL LIQUID TRANSITION

2007 ◽  
Vol 06 (03n04) ◽  
pp. 173-177
Author(s):  
YU. G. ARAPOV ◽  
S. V. GUDINA ◽  
G. I. HARUS ◽  
V. N. NEVEROV ◽  
N. G. SHELUSHININA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Gas ◽  
Quantum Hall ◽  
Zero Magnetic Field ◽  
Double Quantum ◽  
Ballistic Regime ◽  
2D Electron Gas ◽  
Double Quantum Well ◽  
Liquid Transition ◽  
Low Magnetic Field

The resistivity (ρ) of low mobility dilute 2D electron gas in an n- InGaAs / GaAs double quantum well (DQW) exhibits the monotonic "insulating-like" temperature dependence (dρ/dT < 0) at T = 1.8–70 K in zero magnetic field. This temperature interval corresponds to a ballistic regime (kBTτ/ħ > 0.1–3.5) for our samples, and the electron density is on an "insulating" side of the so-called B = 0 2D metal–insulator transition. We show that the observed features of localization and Landau quantization in a vicinity of the low magnetic-field-induced insulator–quantum Hall liquid transition is due to the σxy(T) anomalous T-dependence.

scholarly journals Low-Frequency Instability Induced by Hopf Bifurcation in a Single-Phase Converter Connected to Non-Ideal Power Grid

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 62871-62882
Author(s):  
Hong Chen ◽  
Wenqian Yu ◽  
Zhigang Liu ◽  
Qixiang Yan ◽  
Ibrahim Adamu Tasiu ◽  
...  
Keyword(s):  
Hopf Bifurcation ◽  
Single Phase ◽  
Power Grid ◽  
Low Frequency ◽  
Frequency Instability ◽  
Phase Converter ◽  
Low Frequency Instability

Experimental investigation of theoretical stability regions for ultra-low frequency oscillations of hydropower generating systems

Energy ◽  
2019 ◽  
Vol 186 ◽  
pp. 115816 ◽  
Author(s):  
Weijia Yang ◽  
Jiandong Yang ◽  
Wei Zeng ◽  
Renbo Tang ◽  
Liangyu Hou ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Low Frequency ◽  
Stability Regions ◽  
Low Frequency Oscillations

scholarly journals Exploring the links between volcano flank collapse and the magmatic evolution of an ocean island volcano: Fogo, Cape Verde

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mélodie-Neige Cornu ◽  
Raphaël Paris ◽  
Régis Doucelance ◽  
Patrick Bachélery ◽  
Chantal Bosq ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Frequency ◽  
Frequency Instability ◽  
Cape Verde ◽  
Magma Storage ◽  
Ocean Island ◽  
Flank Collapse ◽  
Time Space ◽  
Before And After ◽  
Low Frequency Instability

AbstractMass-wasting of ocean island volcanoes is a well-documented phenomenon. Massive flank collapses may imply tens to hundreds of km3 and generate mega-tsunamis. However, the causal links between this large-scale, low-frequency instability, and the time–space evolution of magma storage, crystal fractionation/accumulation, lithospheric assimilation, and partial melting remains unclear. This paper aims at tracking time variations and links between lithospheric, crustal and surface processes before and after a major flank collapse (Monte Amarelo collapse ca. 70 ka) of Fogo volcano, Cape Verde Islands, by analysing the chemical composition (major, trace elements, and Sr–Nd–Pb isotopes) and age-controlled stratigraphy (K–Ar and Ar–Ar dating) of lavas along vertical sections (Bordeira caldera walls). The high-resolution sampling allows detecting original variations of composition at different time-scales: (1) a 60 kyrs-long period of increase of magma differentiation before the collapse; (2) a 10 kyrs-long episode of reorganization of magma storage and evacuation of residual magmas (enriched in incompatible elements) after the collapse; and (3) a delayed impact at the lithospheric scale ~ 50 kyrs after the collapse (increasing EM1-like materiel assimilation).

Low-frequency instability in semi-insulator GaAs

1966 ◽  
Vol 54 (6) ◽  
pp. 890-891 ◽  
Author(s):  
J. Bohm ◽  
G.W. Farnell
Keyword(s):  
Low Frequency ◽  
Frequency Instability ◽  
Low Frequency Instability
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