Many-body effects in the formation of multiply charged ions in a strong laser field
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ManyBody Effects in the Formation of Multiply Charged Ions in a Strong Laser Field B. A. Zona,b,*, A. S. Korneva,**, and E. B. Tulenkoa,*** a
Voronezh State University, Voronezh, 394006 Russia Belgorod State University, Belgorod, 308015 Russia *email: [email protected] **email: a[email protected] ***email: [email protected]
b
Received May 13, 2010
Abstract—Some of the manybody effects in the formation of multiply charged ions in a laser field have been taken into account: inelastic tunneling, collective tunneling, and magnetic moment projection relaxation of the atomic core. Strong fields with an intensity exceeding 1017 W cm–2 are considered when the magnetic component of the laser field acts on the free motion of a photoelectron; therefore, the formation of multiply charged ions through rescattering becomes unlikely. Numerical calculations have been performed for Ar9+… Ar13+, Kr19+… Kr23+, Rb10+, and Rb11+ ions. A significant contribution of collective tunneling, which was not observed in weaker fields investigated previously, has been revealed. Allowance for collective tunneling is shown to reduce the intensity leading to saturation by more than 10%. In this case, the yield of multiply charged Rb ions changes by an order of magnitude, while the yield of multiply charged Ar and Kr ions changes by more than a factor of 2. Comparison with experimental data on the formation of argon ions under the action of a linearly polarized laser pulse is made. DOI: 10.1134/S1063776110120058
1. INTRODUCTION In recent years, the formation of multiply charged atomic ions (MCIs) in a superstrong laser field with an intensity as high as 1019 W cm–2 has been actively stud ied experimentally [1–8]. Relativistic effects begin to manifest themselves in such intense fields. The first effect of this kind is related to the action of the mag netic component of the laser light field on the motion of a free electron. This effect should be considered as relativistic, because the Lorentz force is known to be inversely proportional to the speed of light. As a result of the action of the Lorentz force, the motion of an electron in the field of a light wave ceases to be recti linear; its trajectory takes a figureofeight shape [9]. As a consequence, the rescattering processes, which played a major role in the formation of multiply charged ions in less intense fields [10, 11] when impact ionization took place as a result of photoelectron acceleration in a laser field with the formation of highercharge ions, now become less significant. An experimental confirmation of the suppression of res cattering by relativistic effects was pointed out in [1, 2, 4] and was studied most extensively in [7]. Since the rescattering process ceases to be domi nant, multiply charged ions are formed through the direct action of a laser field on an atom or ion. The existing tunneling theory [12–15], known as the ADK theory, along with its relativistic generalization [16,
17], is a singlebody one. Therefore, the formation of multiply charged
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