ABSTRACT
A prototype C(6+) injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.
Subject(s)
Carbon , Lasers , Radiotherapy/instrumentation , Radiotherapy/methods , SynchrotronsABSTRACT
Duration-controlled amplified spontaneous emission with an intensity of 10(13) W/cm(2) is used to convert a 7.5-microm -thick polyimide foil into a near-critical plasma, in which the p -polarized, 45-fs , 10(19) -Wcm (2) laser pulse generates 3.8-MeV protons, emitted at some angle between the target normal and the laser propagation direction of 45 degrees . Particle-in-cell simulations reveal that the efficient proton acceleration is due to the generation of a quasistatic magnetic field on the target rear side with magnetic pressure inducing and sustaining a charge separation electrostatic field.
ABSTRACT
We developed a new absolute wavelength calibration system that uses machine vision for measurement of low-repetition-rate, short-pulse-duration (10-Hz, 5-ns) tunable lasers. Weak fluorescence from an iodine cell was measured by use of machine vision as a spatially gated integrator, and a pulsed dye-laser wavelength was calibrated with an accuracy of +/-0.005 nm , which is precise enough for differential absorption lidar application.
ABSTRACT
A new deformable mirror control system is developed. This system consists of a deformable mirror, a CCD camera, an image processor, a computer, and actuator drive power supplies. A genetic algorithm is adopted as a control algorithm to obtain an optimum surface profile of the deformable mirror. A circular cross-sectional Gaussian beam was transformed into a beam with a rectangular contour using this system. Although the transfer function of this system is complicated and unknown, this system can be used to obtain the optimum beam profile within the achievable limits of a deformable mirror.
ABSTRACT
We developed a deformable mirror with nine actuators for transformation of a laser beam intensity profile. A circular-cross-section Gaussian beam was successfully transformed into a rectangular-cross-section beam by the deformable mirror with conservation of spatial coherency.
