Basic studies of the generation and collective motion of pair-ion plasmas

Abstract

A fullerene pair-ion plasma without electrons is generated and electrostatic modes propagating along magnetic-field lines are externally excited in the range of low frequencies. It is found that four kinds of wave modes, including theoretically unexpected ones, exist in the plasma, and the phase lag between the density fluctuations of positive and negative ions strongly depends on the frequency. In order to illuminate further collective motion of pair-ion plasmas in the range of high frequencies, a concept of a hydrogen pair-ion plasma consisting of only H+ and H− is proposed and an experimental configuration is presented. On the basis of the production of a hydrogen plasma by Penning ionization gauge discharge, the principles of ion cyclotron resonance and E×B drift motion are shown to be effective for ion-species analysis/selection and separated electron detection from negative ions in the generation of pure hydrogen pair-ion plasmas.

Electrostatic modes in multi-ion and pair-ion collisional plasmas

“…In the experiments [1][2][3][4][5] due to the specific filtering mentioned above, only pair ions are collected in the chamber, and it is believed that electrons are generally absent. The arguments supporting this opinion are convincing and, hence, we accept the mentioned filtering as a fact.…”

“…Yet, the IAW also seems to be problematic because it should not appear in the perfectly antisymmetric pair-ion plasma in question here ͑i.e., with two ion groups with equal masses and temperatures, but opposite charges͒. However, specific conditions in the experiments [1][2][3][4][5] related to the different processes ͑electron impact emission and attachment͒ involved in the production of the positive and negative ions, reveal a small disparity in the two temperatures, and this should in principle allow for an electrostatic acoustic mode to develop.…”

“…The very recent successful production of pair-hydrogen plasma 5 is even more attractive because of the small ion mass and the obvious consequences related to this. This indicates that the experimental and analytical efforts in this particular field will increase even further.…”

“…In the recent past, there has been a lot of activity on the theory and the experiments dealing with such plasmas, initiated by a series of works describing the experimental production of pair ions. [1][2][3][4][5] The ions in question are in fact, C 60 Ϯ produced in simultaneous processes of impact ionization and electron attachment, that are further collected by a magnetic filtering effect, i.e., by a diffusion in the radial direction ͑perpendicular to the magnetic field lines͒. In this way the ions are first separated from the electrons, and then collected through an annular hole ͑with 3 cm diameter͒, due to a subsequent downstream along the magnetic lines, in a very narrow and elongated chamber ͑90 cm in length, and with an 8 cm diameter͒.…”

Shear flow-driven electrostatic instabilities in low density and low temperature pair-ion plasmas with and without electrons

“…1 Efforts have also been made to produce PI plasma of hydrogen ions (H þ and H À ). 2 A series of experiments has been performed to produce pair-ion plasmas [1][2][3][4][5] and this activity has generated a lot of interest from theoreticians in this area. As a matter of fact, a few theoreticians 6 have tried to explain the observations of Ref.…”