Dielectronic satellites

Further we present the results of our calculations of the Li- ike iGplasma satellite lines on the basis of QED PT with ab initio zeroth-order approximation for three-quasiparticle systems, together with the optimized Dirac-Fock results and experimental data for comparison. In Table 4 there are displayed the experimental value (A) for wavelength (in A) of the Ti-like lines dielectron satellites to the ls So-ls3p Pi line of radiation in the K plasma, and the corresponding theoretical results (B) PT on 1/Z (C) QED PT (our data) (D) calculation by the AUTOJOLS method, and (E) MCDF [12, 21],... 

TABLE 4. The wavelength (in A) of the ii-like lines dielectronic satellites to the Is S(,-Is3p Pj line of radiation in the K plasma (see text). 

Figure 12.4 shows the laser intensity dependence of X-ray emission spectra measured at a pulse duration of 30 fs with C = 5 x 10-6. As the laser intensity increased, the X-ray yields increased in proportion. The Rydberg He-like lines from the lsnp-ls2 (n = 3-6) transitions and the dielectronic satellites from the 1 Is2 transition were especially enhanced, which shows that highly excited states of He-like Ar ions were produced due to intensive ion-election collisions. 

Dielectronic satellites can affect the precision of measurements. The lithiumlike resonances directly concern this research due to their close location to the helium-like resonances and their relatively large electron-impact cross section for... 

Fig. 7.3. X-ray spectra in the vicinity of the n = 2, 3 and 4 resonance lines, W2 (top), W3 (middle) and W4 (bottom), showing the n = 2 dielectronic satellites k and j, and n = 2 inner-shell satellites q, r, s, and t, along with the related higher n satellite groups An, Bn and Cn The Ab dielectronic satellite group associated with wb is also visible, along with two high n neon-like Mo32+ lines (see next section)...

The k and j satellites are the strongest dielectronic satellites to the He-like lines, the q, r, s and t satellites have strong contributions due to inner-shell excitation from the Li-like ground state. Besides the dominant collisional excitation of He-like ions in the ground state, recombination processes (radiative, dielectronic and charge exchange) of H- and He-like ions, inner-shell excitation of the Li-like ions and, in the case of the z line, also inner-shell ionization process contribute to the intensity of the He-like lines. We will discuss these processes in detail. 

NIFS databases are widely used directly and through IAEA Genie (only for excitation and ionization cross-sections). New molecular databases will be open soon. A new database for dielectronic satellite lines has been created. In order to store your data in our databases, we are grateful if you send us your numerical data which have been published in a Journal. Organized international collaboration for database would be more efficient for data evaluation and data compilation. 

Satellite lines These are weaker lines arising from doubly excited ions of higher ionization states. The satellite lines of H-like ions are due to He-like ions, those of He-like ions are due to Li-like ions and so on. For example, transitions in Li-like ions of the type Is nlnT Is nT will appear as a satellite to Is nl-ls resonance transitions in He-like ions (Figure 11). The nT electron is a spectator electron. Due to the presence of this electron. Coulomb shielding decreases, which results in the transition occurring at a slightly lower energy than that of the resonance transition. Since two electrons are involved in such transitions (one active, one spectator), these lines are also referred to as dielectronic satellites. 

A wide variety of plasma diagnostic applications is available from the measurement of the relatively simple X-ray spectra of He-like ions [1] and references therein. The n = 2 and n = 3 X-ray spectra from many mid- and high-Z He-like ions have been studied in tokamak plasmas [2-4] and in solar flares [5,6]. The high n Rydberg series of medium Z helium-like ions have been observed from Z-pinches [7,8], laser-produced plasmas [9], exploding wires [8], the solar corona [10], tokamaks [11-13] and ion traps [14]. Always associated with X-ray emission from these two electron systems are satellite lines from lithium-like ions. Comparison of observed X-ray spectra with calculated transitions can provide tests of atomic kinetics models and structure calculations for helium- and lithium-like ions. From wavelength measurements, a systematic study of the n and Z dependence of atomic potentials may be undertaken. From the satellite line intensities, the dynamics of level population by dielectronic recombination and inner-shell excitation may be addressed. 

Inner-shell excitation of the Li-like ion core is the second mechanism to populate the doubly excited levels. For the three electron system, the cascade effect between doubly excited levels is negligible compared to dielectronic recombination. This is justified by the fact that for highly charged ions the states with higher n, n > 3, have large initial populations, so therefore the contribution due to the cascade is negligible. The emission of the satellite line is then ... 

The ratio between the w-line, which is predominantly excited by electron collisions (8.1), and the k-satellite, which is populated by dielectronic recombination (8.2), depends on the electron temperature only. The ratio between the w line and the intensity of the collisional excited Li-like satellites (8.5), depends on the density ratio between the Li-like and He-like ions, as the collisional excitation rates for the allowed transitions in the He-like system and in the doubly excited Li-like system are similar. 

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