Acceleration of high current fully stripped carbon ion beam by direct injection scheme

et al. 2017

Vacuum

The components of a transport line for a laser multicharged ion source are described. Aluminum and carbon multicharged ions are generated by a Q-switched, nanosecond Nd:YAG laser (wavelength λ = 1064 nm, pulse width τ = 7.4 ns, and pulse energy up to 82 mJ) ablation of a target in a vacuum chamber. Time-of-flight and a three-grid retarding ion energy analyzers are used to determine the velocity and the charge state of the ions. A three-electrode cylindrical einzel lens is used to focus the ions. At a distance of 30 cm from the center of the focusing electrode of the einzel lens, Al 1+ and Al 2+ have a minimum beam diameter of ~1.5 mm, while for Al 3+ and Al 4+ the minimum beam diameter is ~2.5 mm. The Simulation of the ion trajectories is done using SIMION 8.1. A high voltage pulse applied to a set of two parallel deflecting plates is used for the pickup of ions with different charge states according to their time-of-flight. An electrostatic cylindrical ion deflector is used for analysis and selection of charges with specific 1

Section: 1faraday Cup and Three-electrode Retarding Field Analyzermentioning

confidence: 99%

Transport line for laser multicharged ion source

Shaim

Rahman

et al. 2017

Vacuum

“…The C 6+ ion beam with a current more than 10 mA was accelerated by the RFQ linac. 19 The ion yield of the laser ion source depends on the laser pulse energy, pulse width, spot size, and target material. The charge separation from the laser plasma can be achieved by creating a uniform ion-accelerating external electric field.…”

Section: Introductionmentioning

confidence: 99%

Carbon multicharged ion generation from laser-spark ion source

Rahman

Review of Scientific Instruments

Elsayed-Ali

2019

Multicharged carbon ions are generated by using a laser-assisted spark-discharge ion source. A Q-switched Nd:YAG laser pulse (1064 nm, 7 ns, ≤ 4.5 × 10 9 W/cm 2 ) focused onto the surface of a glassy carbon target results in its ablation. The spark-discharge (∼1.2 J energy, ∼1 μs duration) is initiated along the direction of the plume propagation between the target surface and a grounded mesh that is parallel to the target surface. Ions emitted from the laser-spark plasma are detected by their time-of-flight using a Faraday cup. The ion energy-to-charge ratio is analyzed by a three-mesh retarding field analyzer. In one set of experiments, the laser plasma is generated by target ablation using a 50 mJ laser pulse. In another set of experiments, ∼1.2 J spark-discharge energy is coupled to the expanding plasma to increase the plasma density and temperature that results in the generation of carbon multicharged ions up to C 6+ . A delay-generator is used to control the time delay between the laser pulse and the thyratron trigger. Ion generation from a laser pulse when a high DC voltage is applied to the target is compared to that when a spark-discharge with an equivalent pulsed voltage is applied to the target. The laser-coupled spark-discharge (7 kV peak voltage, 810 A peak current) increases the maximum detected ion charge state from C 4+ to C 6+ , accompanied by an increase in the ion yield by a factor of ∼6 compared to applying 7.0 kV DC voltage to the target.Published under license by AIP Publishing. https://doi.

“…14 Laser ablation was previously used to generate carbon MCIs. [15][16][17][18][19][20] Kashiwagi et al reported the observation of fully stripped C 6+ ions using Nd:YAG (λ = 1064 nm, τ = 15 ns, pulse energy = 400 mJ, and intensity = 1.6 × 10 11 W cm −2 ). The ions were injected into a radio frequency quadruple linac.…”

Section: Introductionmentioning

confidence: 99%

“…The total number of C 6+ ions injected into the linac was 6.0 × 10 9 with a current of 17 mA. 15 Emission of C MCIs was reported for CO 2 laser (λ = 10.6 µm, τ = 85 ns, and fluence of 1.2 J cm −2 ). 16 An electrostatic deflector ion filter was used to analyze the carbon ions with ion charge up to C 5+ reported.…”

Section: Introductionmentioning

confidence: 99%

Multicharged carbon ion generation from laser plasma

Review of Scientific Instruments

Elsayed-Ali

2016

Carbon ions generated by ablation of a carbon target using an Nd:YAG laser pulse (wavelength λ = 1064 nm, pulse width τ = 7 ns, and laser fluence of 10-110 J cm) are characterized. Time-of-flight analyzer, a three-mesh retarding field analyzer, and an electrostatic ion energy analyzer are used to study the charge and energy of carbon ions generated by laser ablation. The dependencies of the ion signal on the laser fluence, laser focal point position relative to target surface, and the acceleration voltage are described. Up to C ions are observed. When no acceleration voltage is applied between the carbon target and a grounded mesh in front of the target, ion energies up to ∼400 eV/charge are observed. The time-of-flight signal is analyzed for different retarding field voltages in order to obtain the ion kinetic energy distribution. The ablation and Coulomb energies developed in the laser plasma are obtained from deconvolution of the ion time-of-flight signal. Deconvolution of the time-of-flight ion signal to resolve the contribution of each ion charge is accomplished using data from a retarding field analysis combined with the time-of-flight signal. The ion energy and charge state increase with the laser fluence. The position of the laser focal spot affects the ion generation, with focusing ∼1.9 mm in front of the target surface yielding maximum ions. When an external electric field is applied in an ion drift region between the target and a grounded mesh parallel to the target, fast ions are extracted and separated, in time, due to increased acceleration with charge state.