Multicharged carbon ion generation from laser plasma

Abstract

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.

Carbon multicharged ion generation from laser-spark ion source

“…Ions generated in the plasma plume are accelerated to an energy that is about proportional to their charge Zi. 17,18,20,21 However, a subset of ions with low charge states have energies that are slower than that acquired by V and are referred to as slow ions. 21 These ions are generated by multiphoton and collisional processes.…”

“…The generation of Al 4+ and C 4+ by using a ns Nd:YAG laser pulse from solid targets was previously reported. 17,18 An Nd:YAG laser pulse generated carbon ions which were injected into a high current radio frequency quadrupole (RFQ) linac. The C 6+ ion beam with a current more than 10 mA was accelerated by the RFQ linac.…”

Transport line for laser multicharged ion source

“…Ablation of Cu target using 70 mJ (56 J/cm 2 3.5x10 8 W/cm 2 ) laser energy per pulse, maximum charge state generation was Cu 5+ , with the vast majority of ions singly and doubly ionized and 16 % ionization of the plasma [20,21]. An Nd:YAG (wavelength λ = 1064 nm, pulse width τ = 7 ns, and laser fluence of 10-110 J.cm −2 ) was used to produce carbon MCI up to charge state C 4+ with the total maximum charge was ~25 nC [22].…”

Characterization of laser-generated aluminum plasma using ion time-of-flight and optical emission spectroscopy

“…6 The characterization of the different laser-generated ions involves measuring their number, charge state, energy distribution, and angular distribution. These measurements make use of a combination of different techniques such as time-of-flight (TOF) ion detection, 7 electrostatic retarding field analyzers, 8 and different configurations of electrostatic, 8 and magnetic 2 ion spectrometers based on ion bending.…”

“…18 Ion emission for ns laser ablation was characterized by their TOF. 3,8,16,[19][20][21][22][23][24][25][26][27][28][29] The charge state, kinetic energy, and angular distribution of the ions ejected from the laser plasma depend on the laser parameters (e.g., laser pulse energy, wavelength, and pulse duration), the ablated material, and the surrounding environment. 16 The general trend is that increasing the laser pulse energy increases ion generation.…”