Laser ion source with solenoid field

Abstract

Pulse length extension of highly charged ion beam generated from a laser ion source is experimentally demonstrated. The laser ion source (LIS) has been recognized as one of the most powerful heavy ion source. However, it was difficult to provide long pulse beams. By applying a solenoid field (90 mT, 1 m) at plasma drifting section, a pulse length of carbon ion beam reached 3.2 ls which was 4.4 times longer than the width from a conventional LIS. The particle number of carbon ions accelerated by a radio frequency quadrupole linear accelerator was 1.2 Â 10 11 , which was provided by a single 1 J Nd-YAG laser shot. A laser ion source with solenoid field could be used in a next generation heavy ion accelerator. V C 2014 AIP Publishing LLC. [http://dx.A performance of a particle accelerator strongly depends on its ion source. An intense particle source may encourage an accelerator concept to become a next generation accelerator project. Especially for heavy ion accelerators, it has been difficult to provide intense beams with highly charged states. Although there are many operating proton sources with more than a few tens of milliampere in the world, 1,2 there was no project assuming the same amount of current with highly charged heavy ion beam.Currently, electron cyclotron resonance ion source (ECRIS) is the most established ion source and commonly used in major accelerator laboratories. Electron beam ion source (EBIS) is also used to provide highly charged heavy ion beam. Both ion sources typically provide hundreds of microamperes to milliampere range of heavy ions with more than charge state ten. [3][4][5][6][7] On the other hand, laser ion source (LIS) can provide highly charged ion beam with a beam current of more than hundreds of milliampere. However, it has never been adopted by major stream of the accelerator's history since it was proposed in 1969 (Refs. 8 and 9) because of mainly three problems: beam transportation, stability, and short beam pulse.A LIS uses a pulsed high power laser focused onto a solid state target. The laser is absorbed in the target, and target temperature goes up above transition temperature from solid to vapor and plasma in the range of 10 12 W/cm 2 of laser power density. Electrons in the plasma are thermalized by absorbing laser photons by inverse Bremsstrahlung process, and ionization proceeds. Initial plasma density produced by laser ablation is much higher than that of ECRIS and EBIS. At the same time as plasma production, the laser-produced plasma expands to perpendicular to the target surface. 10 Also, plasma adiabatically expands to both transverse and longitudinal direction. This expansion makes ion beam pulse from nanosecond-to microsecond-range. Current density and pulse width of the plasma follow the relationships below during expansion T / L;(1) q / L À3 ;( 2) where, T, q, and L are pulse width, ion current density at an ion extraction point, and plasma drift distance which is the length between the target and the ion extraction point, respectively. In case short pulse wid...

Laser ion source for high brightness heavy ion beam

“…As a result, space charge force in a low energy transport section can be avoided and very intense beam can be captured by strong focusing force of the RFQ. We have demonstrated to accelerate more than 5 × 10 10 of C 6+ ions with a single 2 J laser shot [11]. This scheme is one of unique applications of laser ion source [12].…”

Effect of Solenoidal Magnetic Field on Time Evolution of Ion Beam Emittance in Laser Ion Source

“…A laser ion source can supply a high current pulse beam and is proposed to provide an ion current that satisfies these requirements. In addition, the beam current can be enhanced by applying a solenoidal magnetic field to the laser ion source [7][8][9]. However, the effect of the solenoidal magnetic field on beam emittance has not been clarified.…”

Influence of Magnetically Confined Plasma on the Muzzle Velocity of Gun Projectile

“…The magnetic field can constrain the motion of the plasma in the gun [17]- [20], and then affect the internal ballistic characteristics of the gun by affecting the airflow in the gun chamber. Magnetic confined plasma technology is relatively mature and has applications in many aspects, such as magnetohydrodynamic (MHD) power generation [21]- [23], nuclear fusion [18], [24], [25], laser plasma source [26]- [28], and astrophysics [19], [20], [29]. Nonetheless, few people in and out of the country have applied magnetically confined plasma to improve the muzzle velocity of guns.…”