Drift instability in a positive ion–negative ion plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 949-952 ◽  
Author(s):  
M. ROSENBERG ◽  
R. L. MERLINO
Keyword(s):  
Negative Ions ◽  
Local Approximation ◽  
Magnetized Plasma ◽  
Negative Ion ◽  
Positive Ions ◽  
Ion Plasma ◽  
Drift Instability ◽  
Ion Species ◽  
Positive Ion ◽  
Linear Kinetic Theory

AbstractDrift wave instability in a magnetized plasma composed of positive ions and negative ions is considered using linear kinetic theory in the local approximation. We consider the case where the mass (temperature) of the negative ions is much larger (smaller) than that of the positive ions, and where the gyroradii of the two ion species are comparable. Weak collisional effects are taken into account. Application to possible laboratory parameters is discussed.

Current-driven drift wave instability in a collisional dusty negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1113-1116 ◽  
Author(s):  
M. ROSENBERG
Keyword(s):  
Negative Ions ◽  
Negative Ion ◽  
Drift Waves ◽  
Charged Dust ◽  
Wave Instability ◽  
Nonuniform Plasma ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Magnetic Field ◽  
Linear Kinetic Theory

AbstractThe excitation of drift waves by an electron current parallel to the magnetic field is investigated in a nonuniform plasma composed of electrons, positive ions, negative ions, and massive, negatively charged dust. Electrostatic drift waves with frequencies smaller than the ion gyrofrequencies and wavelengths larger than the ion gyroradii are considered. Linear kinetic theory is used, and collisions of charged particles with neutrals are taken into account. The present results may be relevant to laboratory collisional magnetoplasmas containing negative ions and dust.

Note on radiationless transitions involving three-body collisions

1936 ◽  
Vol 32 (3) ◽  
pp. 482-485 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Continuous Spectrum ◽  
Negative Ions ◽  
Bound State ◽  
Excess Energy ◽  
Negative Ion ◽  
Positive Ions ◽  
Continuous State ◽  
Direct Formation ◽  
Three Body ◽  
Positive Ion

When an electron makes a transition from a continuous state to a bound state, for example in the case of neutralization of a positive ion or formation of a negative ion, its excess energy must be disposed of in some way. It is usually given off as radiation. In the case of neutralization of positive ions the radiation forms the well-known continuous spectrum. No such spectrum due to the direct formation of negative ions has, however, been observed. This process has been fully discussed in a recent paper by Massey and Smith. It is shown that in this case the spectrum would be difficult to observe.

scholarly journals Dissociation, recombination and attachment processes in the upper atmosphere II. The rate of recombination

1939 ◽  
Vol 170 (942) ◽  
pp. 322-340 ◽  
Keyword(s):  
Negative Ions ◽  
Neutral Molecule ◽  
Upper Atmosphere ◽  
The Other ◽  
Negative Ion ◽  
Neutral Atoms ◽  
Attachment Rate ◽  
Additional Advantage ◽  
Positive Ions ◽  
Positive Ion

The ionized regions of the upper atmosphere include, not only neutral atoms and molecules, electrons and positive ions, but also negative ions. Of these, electrons are alone effective in producing reflexion of wireless waves; so that an electron attached to a neutral molecule to form a negative ion is as effectively removed from active participation in these phenomena as one recombined with a positive ion to form a neutral molecule. The decay of electron density at night has been attributed by some authors to recombination with positive.ions and by others to attachment by neutral molecules. The first process is in agreement with the observed law of decay and has the additional advantage of making it easily possible to understand the formation of layers of concentrated ionization; on the other hand, the chance of attachment to a molecule per impact would have to be extremely small for the attachment rate to be negligible, since the number of collisions per second with neutral atoms is very much greater than with positive ions.

scholarly journals A new process of negative-ion formation. IV

1938 ◽  
Vol 168 (932) ◽  
pp. 103-122 ◽  
Keyword(s):  
Negative Ions ◽  
Senior Author ◽  
Negative Ion ◽  
The Past ◽  
Ion Formation ◽  
Positive Ions ◽  
New Process ◽  
The Difference ◽  
To Come ◽  
Positive Ion

The three previous papers of this series (Arnot and Milligan 1936 b ; Arnot 1937 a, b ) contain an account of experimental work which led the senior author to propose a new process of negative-ion formation. This process is the formation of negative ions at metal surfaces by bombardment of the surface with positive ions, the negative ion being formed by the positive ion capturing two electron from the surface. Further work carried out during the past year, which is described in this paper, has revealed a new variation of the above process. In this latter process the impinging positive ion causes an adsorbed atom on the surface to come off as a negative ion. It is believed that this newer process is essentially similar to the process previously reported, the difference being due merely to the transference of excitation energy from the incident positive ion, after its capture of an electron, to the atom adsorbed on the surface. The discovery of this second effect was made independently by Sloane and Press (1938), although they attribute it to a different process.

scholarly journals The formation of negative ions by positive-ion impact on surfaces

1938 ◽  
Vol 168 (933) ◽  
pp. 284-301 ◽  
Keyword(s):  
Ionization Chamber ◽  
Metal Surfaces ◽  
Negative Ions ◽  
Negative Ion ◽  
Distribution Analysis ◽  
Positive Ions ◽  
Mass Spectrograph ◽  
Quantal Theory ◽  
Double Mass ◽  
Positive Ion

The quantal theory of negative ions has now been developed considerably (Massey and Smith 1936; Massey 1938), but on account of difficulties of computing it is usually necessary to assume rather than to prove that a given ion exists, and then to discuss the probability of its formation by different processes. The work described here is a contribution to the experimental side of this subject. It had its origin in a projected attempt to measure the capture cross-section of mercury atoms for electrons, as a verification of Massey and Smith's (1936) then unpublished theory of this process. In considering this it became clear that the experiment would be one of unusual difficulty. Before proceeding with it, therefore, it was decided to verify the existence of Hg - as a stable entity, which is assumed in the quantal theory. this was in doubt since Stille (1933), in some careful experiments, had recently failed to obtain it from the plasma of various forms of discharge through mercury vapour, although it is known that negative ions tend to accumulate in such regions (Emeleus and Sayers 1938). Whilst one of us was repeating his experiments, with modifications which led to essentially the same results and will be describes elsewhere, Arnot and Milligan (1936 b ) reported that they had obtained Hg - by bombardment of metal surfaces with Hg + . A comparison of their work with our own showed only one essential point of difference, namely that the construction of their apparatus did not permit of degassing in situ , a condition satisfied with our tubes. Both for this reason and because of the intrinsic importance of their discovery it was thought desirable to repeat part of their work, with apparatus geometrically similar in electrode construction, but capable of being degassed in a furnace under vacuum. We were again unable to obtain Hg - after the apparatus had been degassed and in operation for a short of that of Hg - was obtained. There were, however, always present several light negative ions, which had the excess energies found by Arnot and Milligan (1936 b ) with Hg - . The conditions under which these were formed led us to suppose that they were produced by bombardment of the metal surfaces by mercury positive ions (Press 1937; Sloane 1937) and not capture of electrons by positive ions of the same species, the process suggested by Arnot and Milligan (1936 b ). The existence of a process of this type, which may be conveniently termed "sputtering" (Sloane and Press 1938), is also implied by some earlier work by J. S. Thompson (1931) which has, so far as we know, never been published in detail. It is, however, impossible to decide definitely ion (e. g. CO - ) when it hits the surface, so long as one is producing the negative ions on a metal surface in a plasma or ionization chamber. One cannot overlook the possibility of the negative ion being formed from its own positive ion, since the latter may be present in the plasma or ionization chamber, and CO + , for example, was in fact shown in our work to be there from the positive-ion mass spectra, although in quantity only a fraction of 1% of Hg + . An unambiguous decision on this point can only be reached by first isolating a particular positive ion by a mass spectrograph, then bombarding a surface by this in a high vacuum , and finally making a mass spectrographic and energy distribution analysis of the resultant negative ions. We have built a double mass spectrograph for this purpose and find that negative ions of one kind possessing energies in excess of that imparted to them by the accelerating fields can be produced by bombardment with positive ions of another kind (Sloane and Press 1938). An account of the experiments with the single mass spectrograph is given in 1. the experiments with the double mass spectrograph are described in 2.

Plasma sheath evolution from perturbed electrodes in a negative-ion plasma. Part 2. Experiment and PIC simulation

1997 ◽  
Vol 58 (3) ◽  
pp. 455-466 ◽  
Author(s):  
SEUNGJUN YI ◽  
YASSER EL-ZEIN ◽  
KARL E. LONNGREN ◽  
TERENCE E. SHERIDAN
Keyword(s):  
Fluid Model ◽  
Negative Ions ◽  
Plasma Sheath ◽  
Negative Ion ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Model Code ◽  
Positive Ions ◽  
Ion Plasma ◽  
Quasineutral Plasma

The two-dimensional spatial and temporal evolution of a plasma surrounding an electrode whose potential is suddenly decreased is experimentally investigated. The electrode contains a localized convex or a localized concave perturbation. The quasineutral plasma consists of positive ions and various proportions of negative ions and electrons. The results are compared and contrasted with those that are obtained numerically using a particle-in-cell (PIC) simulation and those that had previously been obtained using a fluid-model code.

Low-frequency electrostatic waves in a magnetized, current-free, heavy negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
S. H. KIM ◽  
R. L. MERLINO ◽  
J. K. MEYER ◽  
M. ROSENBERG
Keyword(s):  
Large Fraction ◽  
Low Frequency ◽  
Negative Ions ◽  
Wave Mode ◽  
Negative Ion ◽  
Electrostatic Wave ◽  
Electrostatic Waves ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Waves

AbstractWe report experimental observations of a low-frequency (≪ ion gyrofrequency) electrostatic wave mode in a magnetized cylindrical (Q machine) plasma containing positive ions, very few electrons and a relatively large fraction (n−/ne > 103) of heavy negative ions (m−/m+ ≈ 10), and no magnetic field-aligned current. The waves propagate nearly perpendicular to B with a multiharmonic spectrum. The maximum wave amplitude coincided spatially with the region of largest density gradient suggesting that the waves were excited by a drift instability in a nearly electron-free positive ion–negative ion plasma

scholarly journals Mobility of the positive and negative ions in gases at high pressure

1912 ◽  
Vol 86 (584) ◽  
pp. 154-162 ◽  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Mathematical Expression ◽  
Negative Ions ◽  
Negative Ion ◽  
Positive Ions ◽  
Low Pressures ◽  
Positive Ion ◽  
Reduced Pressures

The velocity of ions in gases at reduced pressures was first investigated by Rutherford and by Langevin. Recently the author and others have carried out similar investigations. The results of these investigations show that for the negative ions in air the product of the mobility and the pressure is constant for pressures ranging from 760 mm. to 200 mm. of mercury, but with further reduction the product increases with the reduction of pressure, this increase becoming very great at low pressures. For the positive ions in air the product of the mobility and pressure is constant for pressures investigated between 760 mm. and 3 mm. of mercury. Similar results were obtained for the mobilities of the ions in other gases. The results show that if the ion is an aggregation of molecules, this aggregation becomes, at low pressures, less complex in the ease of the negative ion, while in the ease of the positive ion it persists down to 3 mm. of mercury. The purpose of the present research was the study of the mobilities of both kinds of ions in gases at high pressures. The method of investigation is based on the mathematical expression, developed by Prof. Rutherford, for the current between two plates, assuming that a very intense ionisation exists near the surface of one of the electrodes.

scholarly journals The charges on ions in gases, and the effect of water vapour on the motion of negative ions

1908 ◽  
Vol 81 (550) ◽  
pp. 464-471 ◽  
Keyword(s):  
Royal Society ◽  
Negative Ions ◽  
Liquid Electrolyte ◽  
Negative Ion ◽  
Metallic Surface ◽  
Atomic Charges ◽  
Positive Ions ◽  
Brass Surface ◽  
Monovalent Ion ◽  
Positive Ion

1. In a paper published in the ‘Proceedings of the Royal Society,’ vol. 80, p. 207, January, 1908, a method was given for comparing the charges on ions in liquids and gases. The first set of experiments gave results in accordance with the theory, and it was found that the charge on a positive ion in a gas was double that of a negative ion, the latter being equal to the charge on a monovalent ion in a liquid electrolyte. The ratio of the charges obtained was 2.4 / 1.23. The ions were produced by secondary Röntgen rays emitted by a brass surface, and further experiments have shown that positive ions with double or single atomic charges may be produced, the number of either kind depending on the nature of the secondary rays, which is determined by the state of the metallic surface from which they originate.

scholarly journals The charges on ions produced by radium

1909 ◽  
Vol 82 (551) ◽  
pp. 18-22 ◽  
Keyword(s):  
Direct Determination ◽  
Negative Ions ◽  
Atomic Charge ◽  
Great Accuracy ◽  
Liquid Electrolyte ◽  
Negative Ion ◽  
Positive Ions ◽  
Standard Pressure ◽  
Positive Ion

In a paper on “The Charges on Positive and Negative Ions in Gases,” Prof. Townsend has described a method for the direct determination of the quantity N e , where N is the number of molecules in a cubic centimetre of a gas at standard pressure and temperature and e the charge on an ion. His experiments were carried out on ions produced by the action of secondary Rontgen rays, and he showed that for negative ions the method led with great accuracy to the value 1.23 x 10 10 for N e , the same as that for NE, where E is the charge on a monovalent ion in a liquid electrolyte. For positive ions the value obtained in the first set of experiments was 2.4 x 10 10 , but subsequently with less penetrating secondary rays it was found to be as low as 1.26 x 10 10 . It would therefore appear that the positive ions have in some cases a single and in others a double atomic charge, whereas the charge on the negative ions is always the same. With a view of testing the theory for ions produced by radium, experiments have been made with an apparatus precisely similar to that used by Prof. Townsend, and the results obtained confirm the reliability of the method. After making due allowance for experimental and other known sources of error the positive ion appears to behave at all pressures and under all forces in accordance with the theory, but in the case of the negative ion some considerable deviations were observed, if the gas is very dry, but these disappear as soon as some water vapour is added.

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