Temperature Hydrogen Plasma Research Articles

Radiation Charge Exchange and Radiation Ion-Atom Recombination as a Source of Continual E-M Radiation from Astrophysical Plasma

We show that for the study of emission from weakly ionized low temperature hydrogen plasmas, the processes A+ + A → A+ + A + ħω and A+ + A → A+2 + ħω (where A denotes a neutral atom in ground state and, A+ and A+2 atomic and molecular ions) must be treaded as a source of continual electro–magnetic radiation from low temperature plasma. Both reaction channels are treated separately and the corresponding total and separate spectral intensities are determined for hydrogen plasma at T < 10000K. The obtained results have been also compared with the corresponding spectral intensities for electron–ion bremsstrahlung and electron–ion photorecombination.

New density diagnostic method based on emission line intensity ratio of neutral hydrogen in an ionizing phase plasma

For high temperature hydrogen plasmas in the ionizing phase, the population density of the excited levels has been calculated for a wide range of electron densities and temperatures. In the calculation we employed the most recent and reliable cross-section data for excitation between discrete levels and the ionization cross-section data from these levels. The line intensity ratios calculated under conditions of optical thinness are presented graphically for the Lyman and Balmer series lines. The intensity ratios are found to be rather insensitive to the electron temperature for temperatures higher than 10 eV. These values may be used for determining the electron density in the region of 1017 ⪅ ne ⪅ 1021 m−3, which is relevant to fusion research plasmas. Radiation loss from the plasma and energy loss from the plasma electrons are also presented for a wide range of electron densities and temperatures.

Kinetic theory of neutral hydrogen atoms penetrating a hydrogen plasma half-space: Analytic solution

Transport of neutral hydrogen atoms in uniform temperature hydrogen plasma half-spaces is considered. Using arbitrary ion distribution functions, analytic neutral solutions are found depending on one spatial and three velocity variables. These are evaluated for a Maxwellian distribution.

Whistler mode noise in Jupiter's inner magnetosphere

The distinctive ‘hat shape’ of equatorial pitch angle distributions constructed from Pioneer 10 and 11 Jupiter observations of energetic electrons Ee > 21 MeV and Ee > 31 MeV at L = 3 is examined from the point of view of pitch angle diffusion by resonant interaction with a band‐limited spectrum of whistler mode noise. In this picture, the pitch angle profiles are consistent with whistler mode noise limited to frequencies below an upper cutoff frequency 2.8 ≲ fc ≲ 4.6 kHz. Equatorial linear growth rates of parallel propagating whistlers are evaluated in a fully relativistic manner for the inner region 3 < L < 10 using previously published models for the spatial distribution of thermal plasma and the energetic electron distributions. The maximum frequency for which wave growth is positive at L = 3 is roughly consistent with that implied by the 21‐ and 31‐MeV equatorial pitch angle profiles. Maximum growth rates computed from the respective energetic electron models span the range 0.1 ≲ γmax ≲ 10 s−1 throughout the inner region. The spectral extent of the whistler mode noise, defined by those frequencies for which γ > 0.5γmax, is approximately 2–10 kHz at L = 3 and falls smoothly to 0.2–2 kHz at L = 10. Raytracing of nonducted whistlers of characteristic frequencies 1–4 kHz generated at the magnetic equator and propagated through a finite temperature (100–400 eV) hydrogen plasma centrifugally confined near the magnetic equatorial plane shows that wave phase speeds decrease to near or below electron thermal speeds before high‐latitude reflection can occur. Wave growth in this case is limited to a disclike region centered about the magnetic equator. The amplitude growth of the most unstable whistlers propagating across the growth region parallel to the magnetic field is ∼exp (3–4). By equating energetic electron radial diffusion injection times to the pitch angle diffusion loss times of electrons in cyclotron resonance with waves of frequencies of maximum unstable growth, the power density of whistler mode noise is estimated to be 10−19±1 G² Hz−1. The balance equation for radial diffusive injection and pitch angle diffusive losses occurring in the presence of whistler mode noise of characteristic growths exp (3–4) yields upper limit estimates for the magnitude of fluctuations about the stably trapped limiting intensities in the region 3 < L < 10. This upper limit is approximately at the 10% level, in reasonable agreement with the smooth radial flux profiles observed during the Pioneer‐Jupiter encounters.

Measurement of ultraviolet Argon(II) transition probabilities

The transition probabilities of twelve Ar(II) lines around 300nm have been measured in a stationary arc experiment at 1 atm. The reported data are based on absolute intensities, calibrated by the continuum radiation of a high temperature hydrogen plasma. For two lines the maximum emission coefficient at 26500 K has been used for an immediate determination of the respective A mn -values. These data serve for temperature measurements at lower arc currents, where the other lines are investigated. The results, the uncertainty of which should be below ±15%, agree satisfactorily with coulomb approximation calculations, but show severe discrepancies as compared with more recent NBS tables.