A. A. Golubev

Multiply charged ions from iodine laser-produced plasma of medium- and high- Z targets

Maximum charge states of ions registered in the far expansion zone from laser-produced plasma ofAl, Co, Ni, Cu, Ta, W, Pt, Au, Pb, and Bi are presented. The Thomson parabola spectrometer was used to display a general view of the ion species of an expanding plasma while detailed ion charge-energy spectra were determined by the cylindrical electrostatic ion energy analyzer. The current densities of highly charged ion groups above 20 mA/cm 2 were measured by use of an ion collector at a distance of ∼1 m from the target. The photodissociation iodine laser system PERUN (A = 1.315 μm, power density up to ∼10 15 W cm -2 ) was employed as a driver.

X-ray spectromicroscopy of fast heavy ions and target radiation

A new technique for X-ray spectromicroscopy of fast heavy ion radiation during the ion interaction with stopping media is presented using focusing spectrometers with spatial resolution. Spherically bent crystals of quartz and mica with small curvature radii, R ¼ 150 mm, and large apertures were used as dispersive elements in experiments on fast Ni ions with energies of 5.9 and 11.2 MeV/u which are being stopped in different media: Ar gas, SiO2-aerogels and solid quartz. Spectrally high (l=Dl ¼ 100023000) and spatially high (up to 10–100mm) resolved Ka-satellite spectra of Ni projectiles as well as of the ionized stopping media were observed. r 2002 Elsevier Science B.V. All rights reserved.

Formation of hollow heavy ion beams in plasma lens

Hollow cylindrical high-energy heavy ion beams are an efficient driver for target irradiation to achieve highly compressed matter. This paper is devoted to the study of how hollow beams form with the use of a plasma lens. Calculations and measurements were performed with a 200 MeV/amu C+6 beam.

Study of the slow ion beam penetrating the low density plasma target

Energy loss of the slow ion beam impacting on a low density hydrogen gas target was measured. A good agreement between the experimental and theoretical results is found. The result of the ion beam passing through a fully ionized hydrogen plasma target is shown too.

Plasma lens for transformation the ITEP heavy ion accelerator with TDI-pseudosparks

Transportation and focusing of intense heavy-ion beams is an important issue for heavy ion beam-driven inertial confinement fusion and physics of high energy densities. Application of plasma lens offers certain advantages over traditional systems based on quadruple lenses. A description of the plasma lens with high-power high-current (up to 400 kA) TDI-pseudosparks as switching elements and experimental results of preliminary studies of plasma lens designed for heavy ion accelerator-accumulated facility TWAC-ITEP are reported. It is shown that a focusing capability of plasma lens depends on a stage of plasma discharge development. In a particular stage it is possible to employ sharp focusing and compress the beam into a very small spot. In other stages when the magnet field is non-linear it is possible to shape various beam configurations, in particular, tube structures. In the report the results of investigations implemented with beams of C+6 and F+6 ions with energy of 200 MeV/a.e.m. are reported. The obtained results are analyzed.

Irradiation of Bypass Diodes up to 2.2E14 Neutron/cm

The FAIR project planned at G.S.I. (Germany) requires the construction of several superconducting accelerator rings. One of the two synchrotron rings, named SIS300, will have dipoles with a central field of 6 T and a ramp rate of 1 T/s. In order to protect these fast-ramping magnets in case of a quench, each of them must be equipped with a diode stack that bypasses the magnet in case it quenches. In order to save time and money on R&D, we decided to use the same diode type as that mounted in LHC magnets. These diodes were previously tested at 77 K up to a fast neutron fluence (F) of 2.8E13 n/cm2 and a dose (D) of 2 kGy which are the expected radiation loads after 20 years of LHC operation. Having no definitive estimation of the losses in the SIS300, we arbitrarily targeted a fluence of 1E14 n/cm2. We irradiated six LHC type diodes at 77 K in six steps. The highest values measured were 1.31 kGy and 2.25E14 n/cm2. Before and after each irradiation step, the forward and reverse voltage characteristics of each diode were measured. This paper reports the results of these measurements, carried out at ITEP (Moscow).

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The results of systematic studies of ion emission from plasmas generated in the focus of laser beams of short wavelengths, short pulse lasers (Nd:glass, 1 ns, 1060 nm; iodine, 0.5 ns, 1st harm.1315 nm 2nd harm.675 nm, 3rd harm.483 nm) are presented. The corpuscular diagnostics were based on (i) Thomson parabola spectrometer to display a general view of the ion spectra, (ii) cylindrical electrostatic ion energy analyzer to determine the detailed charge-energy ion spectra (iii) ion collectors to estimate the current density of the ion fluxes far from the focus. The ion current densities about 1 m from the focus are typically mA/cm 2 . Fairly high charge state (>50+) and simultaneously energetic (>8 MeV) ions were registered. The results are interpreted either in term of a twotemperature model of the expanding plasma or by an ion emission from a dual focal spot including a hot primary focus and a colder peripheral zone.

and 1.3 kGy for the FAIR Project

Spectroscopic techniques were employed to measure the electron density and temperature of a plasma produced by a CO2 laser at input energies close to those achieved in experiments on plasma heating by heavy ion beams in the Maxilac accelerator. The density was ~ (1–2) × 1017 cm−3, whereas the temperature was approximately 20–30 eV near the maximum of the heating radiation pulse and ~ 3 eV after the end of the pulse.

Ion emission from high-Z laser plasmas

The program of experimental work on heavy-ion inertial synthesis [i] includes a complex of investigations on the physics of the interaction of beams of heavy ions with plasma targets, in particular, comparison of the brehmsstrahlung losses of heavy ions in a hot and dense plasma and in cold matter. In this connection the need arises for development of methods of diagnostics of the temperature and density both of a plasma heated by an intrinsically intense ion beam, and of plasma targets, prepared previously using other sources of energy emission [2]. The problem of determination of the parameters of a plasma formed on focussing of an intense beam of heavy ions on plastic targets, can be solved adopting spectroscopic methods of diagnostics which are more convenient in the investigation of such a plasma. One such method is based on the use of the temperature-sensitive relative intensities of the lines. In this case lines are chosen close in wavelength and due to transitions from levels which are populated as a result of radiative-collisional excitation of ions with strongly differing ionization potentials. The sharp dependence on temperature arises as a result of the substantially different temperature ranges of the existence of such ions in conditions where the ionization energy substantially exceeds the thermal energy. Methods of determination of the temperature of a plasma, arising on focussing an intense beam of heavy ions on a target, are conveniently processed on a laser plasma, which permits modeling the experimental conditions realized for the heavy-ion method of heating (T e 1016 cm-S). Specifically therefore, in this work the method of determination of the plasma temperature relative to the intensities of lines belonging to atoms of different multiplicity of ionization was developed as applied to a nonstationary laser plasma.

Diagnostics of a CO2 laser plasma at input energies typical of plasma heating conditions in the Maxilac heavy-ion accelerator

The energy loss of heavy ions in a hydrogen plasma has been measured in an energy range from 1.4 to 6 MeV/u. A z-pinch has been used as a plasma target with a maximum free electron density of 1.5×1019 cm−3. Our data show a strong enhancement of the stopping power of the plasma compared to that of a cold gas with equal density. Charge state analysis of the ions also show a higher charge state of the ions in the plasma target, relative to the cold hydrogen gas targets. A plasma lens effect of the high power z-pinch discharge was observed in our experiments.