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Carbon implantation can be effectively used for axial minority charge carriers’ lifetime control in various silicon bulk and epitaxial planar structures. When carbon is implanted, more stable recombination centres are formed and silicon is not doped with additional impurities, as for example, when irradiated with protons or helium ions. Economically, such a process competes with alternative methods, and is more efficient for obtaining small lifetimes (several nanoseconds). I-3 ion injector with laser-plasma ion source at Institute for theoretical and experimental physics (ITEP) is used as ion implanter in semiconductors. The ion source uses pulsed CO2 laser setup with radiation-flux density of 1011 W/cm2 at target surface. The ion source produces beams of various ions from solid targets. The generated ion beam is accelerated in the two gap RF resonator at voltage of up to 2 MV per gap. Resulting beam energy is up to 4 MV per charge. Parameters of carbon ion beam generated and used for semiconductor samples irradiation during experiments for axial minority charge carriers lifetime control in various silicon bulk and epitaxial planar structures are presented.

The paper presents the results of numerical simulation of the CO₂ MOPA laser scheme which is designed to generate powerful short radiation pulses in the ion source circuit. It is based on the nonlinear nature of the amplification of the master-oscillator pulse radiation, the front of which is formed by a nonlinear absorber. The paper considers the influence of the geometric parameters of the entrance beam in a four-pass amplification scheme. It is shown that for a fixed value of the small signal gain the maximum amplification effect is achieved with a certain formation of the spatial characteristics of the laser beam at the input to the amplifier. So some central uniform part of MO beam which has a Gaussian spatial profile is used in the telescopic amplifier. In this case, despite significant aperture losses, the maximum energy at the output of the amplifier is achieved with optimizing the beam diameter., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

Carbon implantation can be effectively used for axial minority charge carriers lifetime control in various silicon bulk and epitaxial planar structures. When carbon is implanted, more stable recombination centers are formed and silicon is not doped with additional impurities, as for example, when irradiated with protons or helium ions. Economically, such a process competes with alternative methods, and is more efficient for obtaining small lifetimes (several nanoseconds). I-3 ion injector with laser-plasma ion source in Institute for theoretical and experimental physics (ITEP) is used as ion implanter in semiconductors. The ion source uses pulsed CO₂ laser setup with radiation-flux density of 10¹¹ W/cm² at target surface. The ion source produces beams of various ions from solid targets. The generated ion beam is accelerated in the two gap RF resonator at voltage of up to 2 MV per gap. Resulting beam energy is up to 4 MV per charge. Parameters of carbon ion beam generated and used for semiconductor samples irradiation during experiments for axial minority charge carriers lifetime control in various silicon bulk and epitaxial planar structures are presented., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

This work is a part of the development of a laser ion source (LIS) for multiply charged ion injectors. This experiment is devoted to the investigation of the effect of a metal grid on the extracted ion characteristics. The energy spectra of the ions in the plasma expanding into a drift tube with and without a grid have been compared. Plasmas of two different target materials, carbon and tungsten, were generated by the CO2 laser pulses with the focal power density on the target of about 1011 W/cm2. The time-of-flight method with an electrostatic energy analyzer installed just behind the grid is used to measure the charge states and energy distributions of ions. A significant effect of the grid on the ion energy distributions has been observed. This effect depends strongly on the ion mass and should be taken into account when designing a LIS, especially in the case of heavy ions.

Experiments on the irradiation of a carbon target with СО2-laser pulses in the free-running mode at a radiation-flux density of 1.3 × 1011 W/cm2 and the time-of-flight technique for measuring the characteristics of the plasma ion component are described. The characteristics of the ion component of plasma that expands along the normal to the target and the statistical spread of the mean values were obtained. As a result of the measurements, the energy spectra of the plasma expansion and the partial ion currents at a chosen distance of the plasma drift from the target were reconstructed. The high time resolution of this technique made it possible to reconstruct the escape times of individual groups of ions from a heated region on the scale of the duration of the heating laser pulse.

Heavy ion injector I-3 represents two-gap 2.5 MHz resonator with accelerating voltage 2x2 MV. It‘s used with laser ion source for acceleration of heavy ions in wide range of charge to mass ratio. As a result of modernization, injector structure will be supplemented by the second two-gap resonator, rf voltage will be increased to 3x4 MV and accelerated beam structure has to be improved by increasing accelerating frequency to 5 MHz. Design features of upgraded linac and peculiarity of beam dynamics for different types of ions are presented., Proceedings of the 29\textsuperscript{th} Linear Accelerator Conf., LINAC2018, Beijing, China

The design of laser-plasma heavy ion source is described. This ions source is supposed to operate at I-3 and I-4 accelerators at ITEP. Characteristics of ion component of plasma produced by pulses of the CO2 laser were studied, when irradiating a solid carbon target at power density of 10¹¹-10¹² W/cm². Time-of-flight technique using a high-resolution electrostatic energy analyzer was applied to explore charge state and energy distribution as well as partial currents of carbon and tungsten ions. Some results of investigation of influence of cavern formation on charge state of generated ions are presented. This work is of considerable interest in a wide area of applications of accelerated particle beams, including fundamental studies of state of matter in particle colliders (NICA project at JINR), radiation damage simulation and hadron therapy for cancer treatment. The goal of this work is to investigate characteristics of ions in expanding laser plasma and find optimal conditions of target illumination and ion beam extraction. This research is valuable for adapting an intensive beam from laser ion source to the accelerator, improving acceleration efficency and rising the amount of accelerated particles., Proceedings of the 26th Russian Particle Accelerator Conf., RUPAC2018, Protvino, Russia

This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structure

The conception of Multi-purpose Hadrons Facility (MHF) began to be discussed at ITEP in the late ~2010s when ITEP-TWAC facility was intensively exploited for physical and applied research with the use of accelerated proton and ion beams varied in a wide range of operating parameters. Technological developments have continued to expand the scope of beams utilizing in diverse fields of science, medicine, industry and education. The ITEP-TWAC facility was decommissioned in 2012 and continues to remain in a state of waiting for reasonable decision on its recovery and upgrade, but conception of MHF is alive and aims at creating a technological base of particle accelerator technique intended for generation of proton and ion beams, covering the needs of many areas of fundamental, applied and technological research and industrial applications, represents a significant scientific and practical interest for modern and future engineering community. Created MHF environment should obviously be friendly and flexible for collaboration with industry, universities, and other national and foreign labs to provide continuous intelligent and technological progress. The key components of the MHF mission and vision are presented., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

The design of a laser oscillator with a stabilized frequency composition and a stabilized intensity of output radiation is described. The oscillator’s basic component is a TEA CO2 module pumped by a self-maintained discharge and operating in a repetition-rate mode at a frequency of up to 3 Hz. A circuit for the formation of a self-maintained homogeneous discharge in the working volume of a CO2 + N2 + He mixture at atmospheric pressure is the basic component of the gas-discharge module. This circuit is based on the generation of a high-voltage pulse with a special profile, which provides high-reliability excitation of a discharge and pulse-to-pulse reproducibility of the discharge characteristics. The use of a hybrid circuit in the optical oscillator allows selection of a single longitudinal mode in the output radiation spectrum, thus eliminating undesirable interference phenomena, which lead to instability of the instantaneous values of the radiation intensity. During the development of the oscillator, the optimal operating parameters of the hybrid circuit were obtained, which ensure the high quality and reproducibility of the spatiotemporal and energy parameters of laser radiation.

The results of the development of the ITEP accelerator carbon ion injector based on a repetition-rate CO2 laser ion source are described. The improvement includes a modified pulsed HV-feeding generator for the discharge formation in the laser gas mixture. The advanced discharge module ensures essential increase of the laser active volume and specific electrical deposition energy. The comparative computer simulations of the discharge characteristics for the improved and the prototype lasers are applied. The design and the output spatial-temporal parameters of the free-running laser “Malish-M” are shown, so the significant increase of the laser power is reached. The spatial characteristics of the laser beam obtained with diffraction calculations are compared to measured radial distribution of the energy density. The target laser intensity and the different channels of the energy loss of the laser beam in the optical scheme are estimated. Finally, the output C4+ current trace of heavy ion injector as well as the injector scheme are shown.

A set-up of the CO2 “SKATE” and its output characteristics are described. The system is based on a self-sustained gas discharge module with x-ray preionization that ensures reliability and stable repetition rate operation at 1 Hz for a long time. Measurement of the initial electron density in the discharge volume produced by an x-ray gun is presented for different gases and their mixtures, which is of independent interest for some applications of x-ray preionization. Data on measurements of the low-intensity signal gain and laser parameters for a free-running generator configuration are presented as well as long-term operation characteristics. This laser system has been used as a CO2 generator with gigawatt peak intensity and high spatial–temporal characteristics. In particular, the laser can be used as a driver for a source of multicharged ions in contrast to the laboratory prototypes previously investigated.

Experimental and numerical calculation results devoted to development of an optical system for an ion source based on a repetition rate CO2 laser are described. The laser chain consists of a master oscillator, gas absorber cells, and a four-pass amplifier. The optical system provides smooth laser pulses with variable duration and high spatial quality that ensures efficiency for plasma heating and ion generation. The parameters of the plasma ion component measured in the CERN laboratory are applied for a lead target illumination.

The reconstruction of a system of ring-shaped accelerators has been completed at the Institute of Theoretical and Experimental Physics: carbon nuclei have been accelerated in the U-10 synchrotron up to maximum energy 4 GeV/amu C4+ ions from a laser ion source are preaccelerated in the I-3 linear injector up to 1.5 MeV/amu and in the UK booster synchrotron up to 50 MeV/amu, injected via the charge-transfer scheme C4+ → C6+ into the U-10 synchrotron on an increasing magnetic field and accelerated to maximum energy. The basic technological features of the acceleration scheme employed and the results of the first physical experiment with relativistic carbon nuclei are described.

In this article, we present the results of the laser ion source (LIS) for heavy ion high charge state Institute of Theoretical and Experimental Physics terawatt accumulator facility. This LIS is a duty ion source of C+4 for the injector. The main parameters of CO2 laser, vacuum target chamber, ion beam high voltage extraction system, and low energy beam transport line are shown. The stability of the LIS operation is discussed and measured ion beam parameters (ion current, pulse duration, emittance) for different charge states are presented. After the upgrading of the laser cavity, high voltage capacitors, and spark gaps and the installation of a new catalyst regenerator system, the CO2 laser became much more stable and allows long term operation. LIS works about 1 × 106 shots without intervention.

The construction of the Terawatt Accumulator (TWAC) facility is nearly completed at the ITEP in Moscow. All the major milestones have been successfully passed with a beam of carbon ions, except for the final result (the high power beam accumulation), which is on the way. The beam of C4+ ions delivered by the laser ion source is accelerated up to the energy of 300 MeV/amu by two steps—in the linear injector I3 and in the booster synchrotron UK. The accelerated beam is extracted from the UK ring and transferred to the U10 accumulator ring. Non-Liouvillian stripping technique (C4+ ⇒ C6+) is applied for stacking of C6+ batches into the accumulator ring U10. First experiments with extracted beam of ions have started in 2002. Status of the TWAC components, current results of activities aiming at mastering the ion beam stacking technique, and outlook for the TWAC advance are presented.

Experiments have been carried out to optimize the yield of Pb+4 ions from the plasma produced by a 100 J CO2 laser. The laser power density on the target surface was varied between 1010 W/cm2 and 9×1010 W/cm2 by changing the focal spot size. Data on the production of Pb+4 to Pb+10 ions are presented for the 15 and 40 ns laser pulse durations. The 10 mA/80 μs pulses of Pb+4 ions (about 1012 ions per pulse) were directed into an extraction aperture of 3.4 cm in diameter for optimal irradiation conditions. This is comparable with the parameters of the MEVVA ion source. Laser ion sources can be especially attractive due to the absence of the “noise” problem, typical for the MEVVA ion source, and because of the possibility of generating higher charge states. The emittance of the lead ion beam extracted from the laser-produced plasma was measured by using a 5 J laser, which provided plasma parameters (the electron temperature, ion velocities, and the charge state distribution) close to those of the plasma gener...

C6+ ions with energy 200 MeV/nucleon have been accumulated in the chamber of the ring magnet of the U-10 proton synchrotron used as a storage ring in the TWAC setup. A C4+ ion beam from the laser source was first accelerated in the I-3 injector up to 1.3 MeV/nucleon and in the UK booster synchrotron up to final energy with periodicity 3.5 sec. Ions have been accumulated in U-10 using the multiple charge-exchange injection scheme C4+ → C6+. An increase in the ion intensity in the accumulator has been observed during several injection cycles. Experimental data on the attained parameters of the accumulated beam are presented, and the status of the optimization of the accumulation regime is discussed.

Operation of the laser ion source of He-like light ions designed for the first stage of the ITEP Terra Watt Accumulator (TWAC) project is discussed. A 5 J/0.5 Hz rep-rate CO2 laser was used for generation of highly charged light ions. The absolute number of ions with different charge states for carbon and aluminum ion beams has been measured. The obtained number of C+4 ions (∼1011ions/pulse) is sufficient to start the experimental proof of the accelerator scheme of the TWAC project. The investigation of shot to shot stability indicates significant increasing (∼2–3 times) of highly charged ion yield for the first shot onto the fresh target surface with respect to the next shots onto the same spot of aluminum target. This effect was not observed for the carbon target. Experimental results for highly charged light and medium mass (F, Mg, Al, Ca, Ti) ions produced by of 75 J single pulse CO2 laser consisting of a master oscillator and power amplifier are also presented.

The project ITEP-TWAC (Tera Watt Accumulator) being in progress at ITEP (Moscow) requires He-like ions for non-Liouvillean injection into the storage ring to accumulate ≈2·1013 particles with medium masses up to 59Co25+. Powerful lasers were found to be the best choice for those ions production. This work presents the experimental results of highly charge ion generation in plasmas produced by the second harmonic of Nd-glass laser facility with a total energy E ≤ 50 J and pulse duration of about 2.5 ns at GPI (Moscow). Ti and Ta targets were under investigation. An electrostatic ion energy analyzer and an ion charge collector were used to measure the ion charge state spectra at a 3-m distance from the targets. 5·107 He-like Ti ions per cm2 within 1 μs pulse as well as 107 Ta+41 per cm2 within 0.8 μs were observed.

A status overview of the development of laser ion sources suited to heavy ion synchrotrons is presented. The results of experimental and theoretical studies, recently obtained at a number of laboratories, for laser-produced highly charged heavy ions are summarized for plasmas heated by long wavelength lasers. Design of a powerful repetition rate CO2 laser, target interaction chamber, and extraction system suited for reliable long term operation mode with real accelerators is discussed. Requirements for the final performance of the laser ion sources for ion beam injectors at the ITEP-Moscow and CERN accelerator facilities are given.

Dose variations, associated with the 11-year solar activity cycle, seasonal variations of particle fluxes in the Earth's radiation belts at the station orbit, and solar proton events are studied, using prolonged measurements of radiation doses inside orbital station Mir. Daily averages of radiation doses during the declining phase of the 22nd solar cycle and during transition to the 23rd solar activity cycle reached very large values for astronauts and significantly exceed the values calculated according to existing models.

Experimental data are presented concerning the generation and investigation of multiply charged Ti ions from the plasma produced by the second harmonic radiation of a neodymium laser (with an energy under 14 J and a pulse duration of 2.5 ns). A group of ions with multiplicities ranging from +16 to +20 was recorded with an electrostatic energy mass analyser and a collector was employed to measure the ion current of this group, which was found to be equal to {approx}1 mA cm{sup -2} for an ion pulse duration of {approx}0.8 {mu}s. (interaction of laser radiation with matter. laser plasma)

The results of systematic studies of multiply charged Ta ion production with the fundamental frequency of an iodine laser (λ=1.315μm), and its 2nd (0.657μm) and 3rd (0.438μm) harmonics are summarized and discussed. Short laser pulse (350 ps) and a focus spot diameter of 100μm allowed for the laser power densities in the range of 5×1013–1.5×1015 W/cm2. Corpuscular diagnostics were based on time-of-flight methods; two types of ion collectors and a cylindrical electrostatic ion energy analyzer were used. The Ta ions with charge state up to 55+ were registered in the distance of 210 cm; the maximum amplitude of the signal of a high energy ion group was found to belong to the ions with the charge state around 43+, depending on the laser power density. The ion energy distribution was measured for all three wavelengths, however, in a different energy range; the maximum registered ion energy was 8.8 MeV. The occurrence of highly charged ions in the far expansion zone is discussed in view of the mechanism of charge distribution “freezing” during two-temperature isothermal plasma expansion.

A summary of experimental investigations of multicharged ions in the far expansion zone at about 2–3 m, generated from laser-produced plasmas, is presented. The results have been obtained on different laser systems with different wavelengths λ, laser pulse lengths τ and laser energies E. As the targets, the following materials have been used: Al, Cu, Fe, Mo, Ta, Pt, and Pb. In the experiments, we have applied mutually complementary sets of corpuscular diagnostics: charge collectors, an electrostatic ion analyser and Thomson parabola mass spectrograph. It is shown that laser-created plasma can deliver ions with charge states z from 1 to about 50, atomic masses A from 1 to about 200 amu and energies from hundreds of electronvolts to several megaelectronvolts.

Demonstration of matching a laser ion source to the GSI RFQ-Maxilac linear accelerator and the acceleration of a 1.8-mA current beam of Ta10+ ions up to 45 keV/u energy is presented. A 10J/μs CO2 laser has been used to produce a hot plasma plume, emitting highly charged tantulum ions. The correct geometry and potential distribution of the matching section has been designed in accordance with the results of computer simulations by using the AXCEL code. Measurements of the charge state distribution of the accelerated beam indicate that it contains about 70% Ta10+ and 30% Ta11+ ions.

This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structure.

The laser system is a key element of the laser ion source (LIS), significantly influencing source stability and reliability. A 100 J/1 Hz master oscillator-power amplifier CO2-laser system has been designed, built, and tested for a Pb25+ LIS, with the aim of producing the ion beam parameters compatible with an injection chain for the large hadron collider. The results obtained during commissioning of the laser at ITEP and CERN are presented. LIS parameters based on 100 J/1 Hz CO2-laser system and the use of such a source for the ITEP–TWAC project are discussed.

Laser ion source (LIS) is the most intense source of highly charged ions to fill the synchrotron rings in a single turn injection mode. For this reason LIS is used for ITEP TerraWatt Accumulator (TWAC) facility aiming at the production of TerraWatt power level (100 kJ/100 ns) of intense ion beams. Total current density, charge state distribution, and emittance of carbon ion beam generated by the 5 J/0.5 Hz rep-rate CO2 laser were measured at the exit of the source. A low energy beam transport line (LEBT) consisting of Einzel lenses and a buncher were used to match the source to 2 MV/2.5 MHz injector I-3. The C+4 ion beam with current up to 5 mA was accelerated by injector I–3 and about half of this amount have been injected into booster synchrotron. LIS was operated with rep-rate of 0.25 Hz during more than one year with few short breaks. Prolongation of intervention free period of LIS operation up to 3 months was achieved by using of CO2 laser gas mixture regeneration circuit.

A laser ion source using a CO2 laser focused onto a solid target is under study at CERN for the production of high currents of highly charged heavy ions, for possible use in the preinjector for the large hadron collider. A new expansion and extraction layout was installed in this test facility, improving the alignment and making the target to extraction distance more flexible. A two solenoid beam transport system was studied for providing the matching of the beam to a radio-frequency quadrupole. An electrostatic beam transport using gridded electrostatic lenses was designed and constructed as an alternative to a magnetic system. Results show an increased overall current transmission for the electrostatic case. Investigation of the laser parameters required for the production of 1.4×1010 Pb25+ ions in a 5 μs pulse, has been performed using the TIR-1 laser facility at power densities up to 1014 W cm−2 for a focal spot size of 65 μm. The results of the latest scaling are presented.

A terawatt accumulator (TWAC) accelerator/storage ring complex with the laser ion source is in progress at ITEP. The new injector I4 based on the radio frequency quadrupole (RFQ) and interdigital H-mode (IH) linear accelerator is under construction. The front end of the new TWAC injector consists of a laser ion source, an extraction system, and a low energy beam transport (LEBT). The KOBRA3-INP was used for the simulation and optimization of the ion source extraction system. The optimization parameter is the maximum brightness of the beam generated by the laser ion source. Also the KOBRA3-INP code was used for LEBT investigation. The LEBT based on electrostatic grid lenses is chosen for injector I4. The results of the extraction system and LEBT investigations for ion beam matching with RFQ are presented.

The high current, high charge-state ion beam which can be extracted from a laser produced plasma is well suited, after initial acceleration, for injection into synchrotrons. At CERN, the production of a heavy ion beam using a CO2 laser ion source is studied. The latest results of experiments with a tantalum ion beam with charge states up to 23+ and accelerated by a radio frequency quadrupole from 6.9 to 100 keV/u, are presented along with simulations of the low energy beam transport. The ion yield at the desired charge state, the pulse to pulse stability of the ion beam, and the system reliability are all of major interest. Work is under way to replace the low repetition rate free-running laser oscillator by a master oscillator and power amplifier system. The master oscillator is operational and the first results of measurements of its beam quality and stability are presented.