Pulsed-Ion Beams

Very recently Kouchi et al. constructed an ion beam pulse radiolysis system and use it for the study of the LET effect in irradiated polystyrene thin films [106]. The nanosecond pulsed MeV ion beam with the variable repetition rate was obtained by chopping ion beams from a Van de Graaff. Time profiles of the excimer fluorescence from polystyrene thin films, excited by He+ impact, were... 

Basic Studies on Product Analysis and Ion Beam Pulse Radiolysis of Polymers. 102... 

The present chapter describes mainly the radiation effects of various ion beams on spin-coated polystyrene and PMMA films studied mainly by product analysis and by nanosecond ion beam pulse radiolysis. 

Direct measurement of short-lived reactive intermediates by time-resolved spectroscopic methods is very important for understanding the detailed mechanisms of radiation effects. Very recently a new ion beam pulse radiolysis system using optical multi-channel detection has been developed. Although the use of ion beam pulse radiolysis for studying the radiation effects of ion beams on polymers was first reported by us [3, 30], the new system is highly modified for investigating ion beam reactions. Electron beam pulse radiolysis was also carried out complementarily. 

The investigation of the ion beam interaction with polystyrene by means of ion beam pulse radiolysis has the advantage that the reactive intermediates can be directly detected. Time profiles of the excimer fluroescence from ion irradiated polystyrene were measured using the polystyrene thin films. Thus, the transient phenomenon excited by the ion with a definite kinetic energy was observed. 

In Fig. 5, the schematic diagram of the ion beam pulse radiolysis system with an optical emission spectroscope is also shown. The emission produced by the pulsed ion beam impact is detected through a monochromator by a fast photomultiplier tube (PMT) operated in a counting mode. The time profile of the emission is obtained by a coincident measurement between a photon and a... 

Fig. 5. The schematic diagram of the pulsing system and the ion beam pulse radiolysis system with an optical emission spectroscopy. PMT denotes photomultiplier tube HV, high voltage supply CFD, constant fraction discriminator TAC, time to amplitude converter and PH A, pulse height analyzer. From Ref. 36...

Fig. 10. Decay curves observed in electron beam, synchrotron radiation (SR), and ion beam pulse radiolysis of neat n-dodecane liquids...

Radiation effects of ion beams on PMMA films spin-coated on silicon wafers have been studied by ion beam pulse radiolysis. Figure 12 shows typical emission spectra of PMMA irradiated by 1 MeV nitrogen ion beams. The spectra changed drastically on irradiation. 

Very recently LET effects of ion beams on both standard polymers such as polystyrene and low molecular polyethylene model compounds (n-alkanes) have been studied by time-resolved spectroscopic methods, that is, ion beam pulse radiolysis techniques. Further basic studies are necessary so that the detailed mechanisms of ion beams on polymers can be clarified, especially LET effects and high density excitation effects. 

Katsumirra Y. (2001) Ion beam pulse radiolysis study on intra-track reactions in aqueous solutions. Res Chem Intermediates 27 AS) 333-341. 

The basic idea is to ignite and bum a few milligrams of deuterium-tritium fuel by means of high-power laser or ion beam pulses. Two large laser facilities are presently under construction which should demonstrate within the next 5-10 years the feasibility of single micro-explosions. These are the National Ignition Facility (NIF) in Livermore, US and the Laser MegaJoule (LMJ) in Bordeaux, France. 

Continuous primary ion beams are applied in Quadrupole-based SIMS instruments, Magnetic Sector-based SIMS instruments, and Time-of-Flight-based SIMS instruments in which secondary ion beam pulsing is induced through bunching of the secondary ion beam alone (see Section 4.2.3.1.5). 

As indicated earlier, Physical Electronics introduced the HR mode , to provide improved high mass and high spatial resolution at the same time. This is implemented while in the Spectroscopic or Bunched mode through re-design of the LMIG region so as to minimize the energy spread of the primary ion beam pulses. It is quoted that 500 nm spatial resolution at moderate beam currents with sub nanosecond pulse widths is attainable. 

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