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In this study, we investigate an intense-heavy-ion-beam transport through an insulator beam guide by numerical simulation. In our previous papers [Jpn. J. Appl. Phys. 35 (1996) L1127, Jpn. J. Appl. Phys. 37 (1998) L471], we proposed a new system for electron and proton beam transport using an insulator beam guide. We apply this system to a singly charged cesium (Cs+) ion beam transport. An intense Cs+ion beam generates a plasma on the insulator surface. Electrons are extracted from the plasma, and the beam charge is effectively neutralized by the electrons. Electron extraction is self-regulated by the net space charge of the beam. Consequently, an intense Cs+ion beam can be efficiently transported by the proposed system.

This paper presents a simple fitting formula for the numerical screening constants which were obtained for each of 33 materials recently by the authors [Jpn. J. Appl. Phys. 32 (1993) 5681]. Using the screening constants, the atomic energy levels are obtained for the finite-temperature materials based on the screened-hydrogen model. The formula is convenient for users of the screening constants and reproduces well the Hartree-Fock-Slater (HFS) energy levels: the deviations from the HFS levels are 5.99% for n=1 and 55.3% for n=2 by averaging results for the 33 materials. Here nis the principal quantum number.

A high demagnetization rate ?B/?tcan be obtained through fast decoupling of a magnetic field from an electric circuit which generates the magnetic field. Nowadays fast decoupling is possible by present switching technologies. Consequently, a high particle-acceleration gradient can be obtained in an inductive acceleration system compared with that in a conventional induction accelerator. Based on this new proposal, inductive electron acceleration is investigated numerically in this work.

We previously proposed [Jpn. J. Appl. Phys. 34 (1995) L520] a new system for intense-electron-beam transport using an insulator guide which covers the whole beam-transport region. In this paper we present a numerical study of intense-electron-beam transport through an insulator guide whose length is short compared to beam-transport length. Positive ions are extracted in a self-regulated manner from the plasma, generated at the insulator surface, by the electron beam space charge. The ions expand over the transport region, and are extracted from the guide region by the electron beam space charge into the outer region which is not covered by the insulator. Consequently, the beam space charge is neutralized even in the outer region, and the beam propagates effectively in this system.

In this paper we study intense-proton-beam transport through an insulator guide. In our previous papers [Jpn. J. Appl. Phys. 34 (1995) L520, Jpn. J. Appl. Phys. 35 (1996) L1127] we proposed a new system for intense-electron-beam transport using an insulator guide. In contrast to the electron beam, an intense-proton beam tends to generate a virtual anode, because of the large proton mass. The virtual anode formation at the initial stage is prevented by prefilled plasma in this system. During and after this, electrons are extracted from the plasma generated at the insulator surface by the proton beam space charge and expand over the transport area. The proton beam charge is effectively neutralized by the electrons. Consequently, the proton beam propagates efficiently through the insulator beam guide. The electron extraction is self-regulated by the net space charge of the proton beam.

A new electron acceleration mechanism of the superposed laser acceleration which was proposed in a paper [Jpn. J. Appl. Phys. 30 (1991) L1887] is reexamined by numerical analyses and analytical work in order to obtain a scaling law for this mechanism, and to check beam quality and the diffraction effect of laser. In this mechanism, electrons are accelerated by means of two superposed laser beams in which a longitudinal electric field is produced. The numerical analyses show that the acceleration gradient can be 1?10 GeV/m or more depending on the laser parameter employed, when this mechanism is employed appropriately in an acceleration system. In this paper the following important results are obtained: 1) The scaling law is derived in the analytical work and it is numerically reproduced. 2) An electron beam should be collimated well in order to be accelerated well. 3) The diffraction effect of laser beams has a great influence on the electron acceleration. Under the influence of the diffraction, electrons may not be accelerated at all. Drift tubes which lead electrons to only the acceleration region may be required for effective acceleration.

In our previous paper [Jpn. J. Appl. Phys. 35 (1996) L120] we presented a new feature in an intense electron beam transport system with an insulator guide. This paper presents a numerical study of the effect of plasma generation at the insulator guide surface on the transport of an intense electron beam. The plasma at the insulator surface is generated by the local electric field which is created by the beam electrons. Ion extraction from the plasma is delayed by the plasma generation time. The simulation results indicate that 1) the front of the electron beam pulse is used to generate the plasma, and 2) the electron beam transport efficiency is not totally but only slightly degraded.