Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q＋ ions

In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization （or the single capture） of argon associated with single electron loss （or single electron capture） by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.

Multiple ionization of atoms and molecules impacted by very high-q fast projectiles in the strong coupling regime(q/v > 1)

In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime （q/v 〉 1）. The results obtained from this approach are in excellent agreement with the available experimental data. A probable scenario of molecular multiple ionization by fast and very high-q projectiles is discussed. The very small computational time required here and the good agreement with the existing experimental data make it a good candidate for studying the multiple ionization of complex molecules under high linear energy transfers.

Numerical study of the effect of aft-loaded magnetic field on multiple ionizations in Hall thruster

It is assumed that the shift of a strong magnetic field region with a positive gradient from exit plane to outside, namely the transit from a normal loaded magnetic field to an aft-loaded one, enhances the multiple ionization process in the magnetically shielded Hall thruster. To confirm this conjecture, a comparative study is carried out numerically with a particle-in-cell method. The simulation results prove that compared with the normal loaded magnetic field, the application of aft-loaded magnetic field enhances the multiple ionization process. This study further analyzes the ionization characteristics of the transition from low-charged ions to high-charged ions under two magnetic field conditions and the influence of the magnetic strength of aft-loaded magnetic field on the multiple ionization characteristics. The study described herein is useful for understanding the discharge characteristics of Hall thruster with an aft-loaded magnetic field.

Charge Resonance Enhanced Multiple Ionization of H2O Molecules in Intense Laser Fields

We perform a kinetically complete measurement on the fragmentation of Coulomb explosion of 1-120 molecules in intense few-cycle linearly and circularly polarized laser fields. Both the fragmentations of 1t203＋ and H204＋ reveal the concerted pathway of dissociation. The length of the OH bond prior to the Coulomb explosion of both molecular ions is sensitive to the laser pulse duration and laser intensity. However, the bending angle of H-O-H is less sensitive to the pulse duration and laser intensity. We introduce the mechanism of charge resonance enhanced double ionization to elucidate the triple （or quadruple） dissociative ionization dynamics of H20, in which two electrons are non-adiabatically localized at the protons of the precursor ion H2O^＋ （or H2O^2＋） and are released simultaneously due to the over barrier ionization in the combined laser field and molecular ionic potential. Such charge resonance enhanced multiple ionization is not suppressed in few-cycle laser fields and elliptically polarized laser fields.

Multiple Ionization of Argon Induced by Carbon Ions at 20-500 keV/u Energies

We measure the multiple ionization cross-section ratios Rk1 of Ar impacted by Cw＋ （q= 1-3） ions in the energy range of 20-500 keV/u. The measured ratios Rkl increase with the projectile energy at lower energies, and reach the maximum at energies of 50-150 keV/u, then decrease for higher energies, We also use the classical over barrier ionization model to calculate the ratios Rk1, and the calculation results are in good agreement with the data, which suggest that the multiple ionization process is described by the sequential over-barrier ionization process,

Nd L-shell x-ray emission induced by light ions

The L-shell x-ray of Nd has been obtained for 300-600 keV He2+ions impacting,and compared with that produced by H+and H2+ions.The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300-400 keV.It is found that the energy of the distinct L-subshell x-rays has a blue shift.The relative intensity ratios of Lβ_(1,3,4)and Lβ_(2,15)to Lα_(1,2)x-ray are enlarged compared to the atomic data,and they decrease with the increase of the incident energy,and increase with increasing the effective nuclear charge of the incident ions.That is interpreted by the multiple ionization of outer-shells induced by light ions.

Studies of K-shell x-ray energy shifts induced by MeV/u heavy ions

This paper reports that the K x-ray spectra of the thin target 4TAg, 4sCd, 49In and 50Sn were measured by an HPGe semi-conductor detector in collisions with 84.5 MeV 6C4＋ ions. Our experiment revealed the Kα x-ray energy shifts were not obvious and the Kβ1 x-ray energy shifts were about 90-110 eV. The simple model of Burch et al has been previously used to calculate the K x-ray energy shifts due to an additional vacancy in 2p orbit. The present work extends the model of Burch to calculate the x-ray energy shifts of multiple ionized atoms induced by heavy ions with kinetic energy of MeV/u. In addition to our experimental results, many other experimental results are compared with the calculated values by using the model.