Abstract
The pulsed laser-generated plasma in vacuum and at low and high intensities can be characterized using different physical diagnostics. The charge particles emission can be characterized using magnetic, electric and magnet-electrical spectrometers. Such on-line techniques are often based on time-of-flight (TOF) measurements. A 90° electric deflection system is employed as ion energy analyzer (IEA) acting as a filter of the mass-to-charge ratio of emitted ions towards a secondary electron multiplier. It determines the ion energy and charge state distributions. The measure of the ion and electron currents as a function of the mass-to-charge ratio can be also determined by a magnetic deflector spectrometer, using a magnetic field of the order of 0.35 T, orthogonal to the ion incident direction, and an array of little ion collectors (IC) at different angles. A Thomson parabola spectrometer, employing gaf-chromix as detector, permits to be employed for ion mass, energy and charge state recognition. Mass quadrupole spectrometry, based on radiofrequency electric field oscillations, can be employed to characterize the plasma ion emission. Measurements performed on plasma produced by different lasers, irradiation conditions and targets are presented and discussed. Complementary measurements, based on mass and optical spectroscopy, semiconductor detectors, fast CCD camera and Langmuir probes are also employed for the full plasma characterization. Simulation programs, such as SRIM, SREM, and COMSOL are employed for the charge particle recognition.
Highlights
The class of charge particle spectrometers based on electrical or magnetic deflections and both on electrical and magnetic deflection systems is large
Ions are generated by the Nd:YAG laser interacting with a solid Ta target and detected using an electron multiplier which output signal is acquired by a fast storage oscilloscope permitting TOF measurement from the start laser shot to the stop ion detection
The on-line spectrometer uses micro-channel plates (MCP) coupled to phosphorus screen and CCD camera, as that used at PALS facility
Summary
The class of charge particle spectrometers based on electrical or magnetic deflections and both on electrical and magnetic deflection systems is large. When the deflection is controlled by a constant magnetic field B placed orthogonally to the incident particle direction, the Lorenz force acts and a rotation on the particle is induced according to the Larmor radius: From this relation it is possible to observe that the particle trajectory depends on the mass-to charge ratio and initial velocity of the particle. The non perfect orthogonality of the incident particle with respect to the magnetic field direction will produce a helicoidally trajectory which radius depends on the component orthogonal and the pitch on the component parallel The use of both electrical and magnetic fields, in stationary regime, permits to discriminate very well the trajectory for the mass-to-charge ratio for high ion. In this paper will be presented four kind of spectrometers employed mainly for analysis of the particles emitted from high-intensity lasers generating plasma in high vacuum
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
