Demonstration of an intense lithium beam for forward-directed pulsed neutron generation.

As an alternative to research nuclear reactors, a compact accelerator-driven neutron generator that uses a lithium beam driver could be a promising candidate since it produces almost no undesired radiation. However, providing an intense lithium-ion beam has been difficult, and it has been thought that the practical application of such a device would be impossible. The most critical problem of insufficient ion fluxes has been solved by applying a direct plasma injection scheme.

Plasma instability inside solenoid with laser ion source.

Using a solenoid with a laser ion source can suppress divergence of the expanding plasma; however, it has been found that the plasma becomes unstable in a certain magnetic field region. In the previous research, instability of the plasma after the solenoid was found. In this study, we investigated how the plasma instability changes inside the solenoid.

Low charge state lithium beam production from chemical compounds with laser ion source.

In recent years, the primary ion source for the Brookhaven National Laboratory has been the laser ion source, which provides many types of ions within a short switching time of several seconds. The task is difficult for other ion sources. In the previous work, we tested metallic lithium as a target material of the laser irradiation.

Laser power density dependence on charge state distribution of Ta ion laser plasma.

Laser power density per pulse, which is commonly expressed with the unit of "W/cm," is an important parameter to characterize ablation plasma. To match a design charge state of heavy ion beam induced by a laser ion source, a laser power density must be carefully chosen. Above around 10 W/cm of laser power density, laser ablation plasma is emitted from the surface of solid material.

Evaluation of magnetic field error in ExtendedEBIS.

The upgrade of the EBIS, called ExtendedEBIS, is now in progress in Brookhaven National Laboratory. Two 5T-superconducting solenoids have been placed in series with 200 mm distance from each other for higher trap capacity and production of polarized He ions. Since the two superconducting solenoids are used, the field error is expected to be larger.

Contribution of material's surface layer on charge state distribution in laser ablation plasma.

To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor.

Iron plasma generation using a Nd:YAG laser pulse of several hundred picoseconds.

We investigated the high intensity plasma generated by using a Nd:YAG laser to apply a laser-produced plasma to the direct plasma injection scheme. The capability of the source to generate high charge state ions strongly depends on the power density of the laser irradiation. Therefore, we focused on using a higher power laser with several hundred picoseconds of pulse width.

Analyses of the plasma generated by laser irradiation on sputtered target for determination of the thickness used for plasma generation.

In Brookhaven National Laboratory, laser ion source has been developed to provide heavy ion beams by using plasma generation with 1064 nm Nd:YAG laser irradiation onto solid targets. The laser energy is transferred to the target material and creates a crater on the surface. However, only the partial material can be turned into plasma state and the other portion is considered to be just vaporized.

Investigation of effect of solenoid magnet on emittances of ion beam from laser ablation plasma.

A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion beams under three conditions where without magnetic field, with magnetic field, and without magnetic field with higher laser energy to measure the beam distribution in phase space.

Creation of mixed beam from alloy target and couple of pure targets with laser.

To create mixed species ion beam with laser pulses, we investigated charge state distributions of plasma formed from both Al-Fe alloy targets and pure Al and Fe targets placed close together. With two targets, we observed that the two kinds of atoms were mixed when the interval of two laser pulses was large enough (40 μs). On the other hand, when the interval was 0.

Ag ion generation irradiated by Nd:YAG laser onto solid target for use of direct plasma injection scheme.

Direct plasma injection scheme (DPIS) is an acceleration scheme which consists of laser ion source and a radio frequency quadrupole linac (RFQ) linac for high current heavy ion acceleration. With this scheme, over 60 mA of carbon and aluminum beam was achieved at the RFQ exit. We are planning to accelerate Ag ions as a heavier material than used previously.

Feasibility study of a laser ion source for primary ion injection into the Relativistic Heavy Ion Collider electron beam ion source.

Charge state 1+ions are required as a primary ion source for Relativistic Heavy Ion Collider-electron beam ion source (RHIC-EBIS) at BNL and laser ion source (LIS) is a candidate as one of the external ion source since low energy and low charge state ions can be generated by lower power density laser irradiation onto solid target surface. Plasma properties of (27)Al, (56)Fe, and (181)Ta using the second harmonics of Nd:yttrium aluminum garnet laser (0.73 J5.

Application of cryotarget to laser ion source.

We examined laser-produced argon plasma as part of a future laser ion source. Rare gases, which are in gas state at room temperature, need to be cooled to solid targets for laser irradiation. We generated solid Ar targets in a similar way used for neon.