K. Sakakibara

Features of ion generation using Nd-glass laser

Charge state and energy distributions of ions generated by a 3J∕30ns Nd-glass laser were measured at a distance of 3.7m from the target for seven different elements of the Periodic Table and for two different laser power densities (of the order of 1011 and 1012W∕cm2). Two groups of elements were found: highly charged ions with ionization potentials in the range of 500–1000eV were registered for all elements between C12 and Fe56; at the same time, ions with about-one-order-less ionization potentials were registered for elements between Ge74 and Ta181. The most probable reason for such a big difference is the recombination losses of ions during laser-produced plasma expansion into vacuum. Verification of recombination losses in the case of Ta181 target has shown no losses at distances longer than 32.5cm from the target, so recombination processes should take place at shorter distances. Current densities, pulse durations, energy ranges, and numbers of ions with different charge states were found for all elem...

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

Acceleration of a 17mA, 100keV∕u C6+ ion beam has been successfully achieved with an radio frequency quadrupole (RFQ) linac by means of “direct injection scheme.” The C6+ beam produced by a laser ion source with a Nd:YAG laser was injected to the high current RFQ linac. It has been experimentally proved that the fully stripped carbon ion beam with a current more than 10mA was accelerated by the RFQ linac.

High current carbon beam production with direct plasma injection scheme

We have been studying a new heavy-ion production technique called “direct plasma injection scheme,” DPIS, since 2000. A new radio frequency quadrupole (RFQ) designed especially for the DPIS was commissioned in 2004 and very intense carbon beam was successfully obtained, reaching more than 60mA accelerated current from the RFQ. Most of the contents of the accelerated beam was carbon 4+ as verified by beam analysis.

Experimental results of DPIS with a new RFQ

We have developed a new heavy ion production system which uses a combination of an RFQ and a laser ion source. Induced plasma by a laser shot is delivered to the RFQ without an extraction electrode. We named this new idea ‘direct plasma injection scheme (DPIS)’. In 2004, a new RFQ was built for demonstrating the capability of the DPIS. After a few months of commissioning period, we could obtain more than 60 mA of carbon beam from the RFQ. This new scheme could be applied to cancer therapy facilities and high energy nuclear physics accelerator complexes.

Analysis of laser-produced heavy ions for direct plasma injection scheme

To accelerate highly charged intense ion beam, we have developed the direct plasma injection scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a radio frequency quadrupole (RFQ) linac without a low energy beam transport (LEBT) line and then beam losses in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60mA) by DPIS with the RFQ specially designed for high current heavy ions. As the next step we will use heavier elements such as Al, Fe, and Ta as targets in laser ion source (using high power laser, for example, glass laser) for DPIS and will examine properties of laser-produced plasma for highly charged ion production.

Direct plasma injection scheme in accelerators.

The idea of direct plasma injection scheme (DPIS) was proposed in 2000. This new technique has been studied and proven to accelerate intense ion beams. To provide medium mass ions with highly charged states, small tabletop solid lasers were used for plasma production. Based on the measured plasma properties, aluminum and carbon ions were accelerated with more than 60 mA of current. The next experiments will use an radio frequency quadrupole designed for q/m=1/6 and explore beam productions using targets up to silver, and future work will explore production up to uranium. The DPIS has been established and is ready to be used with various accelerators which require pulsed high current, high charge state ion beams.

Properties of Laser-Produced Highly Charged Heavy Ions for Direct Injection Scheme

To accelerate highly charged intense ion beam, we have developed the Direct Plasma Injection Scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a RFQ linac without a low energy beam transport (LEBT) line and the beam loss in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60mA) by DPIS with the new RFQ optimized for the high current beam. As the next step we will accelerate heavier elements like Al as target in LIS (using Glass-laser: Max 4.39J/cm2). To obtain very high current Al beam, we examined the properties of the laser-produced Al plasma. Also a comparison of the glass laser and small YAG laser for the DPIS was studied usin a carbon target.

Direct plasma injection scheme in accelerators (invited)

The idea of direct plasma injection scheme (DPIS) was proposed in 2000. This new technique has been studied and proven to accelerate intense ion beams. To provide medium mass ions with highly charged states, small tabletop solid lasers were used for plasma production. Based on the measured plasma properties, aluminum and carbon ions were accelerated with more than 60 mA of current. The next experiments will use an radio frequency quadrupole designed for q/m=1/6 and explore beam productions using targets up to silver, and future work will explore production up to uranium. The DPIS has been established and is ready to be used with various accelerators which require pulsed high current, high charge state ion beams.

Direct plasma injection scheme in accelerators (invited)a)

The idea of direct plasma injection scheme (DPIS) was proposed in 2000. This new technique has been studied and proven to accelerate intense ion beams. To provide medium mass ions with highly charged states, small tabletop solid lasers were used for plasma production. Based on the measured plasma properties, aluminum and carbon ions were accelerated with more than 60 mA of current. The next experiments will use an radio frequency quadrupole designed for q/m=1/6 and explore beam productions using targets up to silver, and future work will explore production up to uranium. The DPIS has been established and is ready to be used with various accelerators which require pulsed high current, high charge state ion beams.