The paper presents the results of statistical studies of ion beam generation in different geometry diodes with explosive emission cathode in a mode of self-magnetic insulation. The experiments were carried out using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (100 ns, 250–300 kV) and bipolar-pulse mode with the first negative (300–600 ns, 100–150 kV) followed by a second positive (120 ns, 250–300 kV) pulse. It is found that the standard deviation of the total energy and energy density of the beam does not exceed 10–11%, while the same shot-to-shot variation in ion current density was found to be 20–30%. The mechanism of the energy density stabilization from pulse to pulse may be associated with the charge exchange between accelerated ions and stationary molecules and formation of accelerated neutrals. We observed a high correlation between the energy density (or total beam energy) and the duration of the first voltage pulse. We performed analysis of Blumlein statistical performance when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. A characteristic feature of Blumlein operation in the double-pulse mode is an excellent reproducibility of breakdown of the preliminary spark gap, the variation in breakdown voltage is <2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar- and unipolar pulse mode is 3–4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we used the first voltage pulse at the output of Blumlein to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a better reproducibility of the first pulse duration, with the time jitter not exceeding 10 ns in a set of 50 pulses.

This paper presents the results of a statistical and correlation analysis of the energy and energy density of an ion beam formed by a self-magnetically insulated diode with an explosive emission cathode. The experiments were carried out with the TEMP-4M accelerator operating in double-pulse mode: plasma formation occurs during the first pulse (negative polarity, 300–500 ns, 100–150 kV), and ion extraction and acceleration during the second pulse (positive polarity, 120 ns, 250–300 kV). Various arrangements of diodes have been investigated: strip focusing and planar diodes, a conical focusing diode and a spiral diode. The total ion beam energy was measured using both a calorimeter and an infrared camera and the beam energy density was measured by the thermal imaging and acoustic diagnostics. The correlation analysis showed that ion current density is only weakly dependent on the accelerating voltage and other output parameters of the accelerator, with the coefficient of determination <0.3. At the same time, in this paper, we have identified that the total energy of the beam and the energy density is strongly dependant on the accelerator output parameters, since the coefficient of determination >0.9. The mechanism governing stabilization of the beam energy density from shot to shot was discovered and attributed to formation of the neutral component in ion beam as being due to charge exchange between accelerated ions and neutral molecules from a neutral layer near the anode surface. Implementation using a self-magnetically insulated diode with an explosive-emission cathode, having an operational lifetime of up to 106 shots, has promising prospects for various technological applications.

This article presents the results of a study on transportation of a pulse ion beam of gigawatt power. This beam is formed by a self-magnetically insulated diode with an explosive-emission cathode. The experiments have been performed using the TEMP-4M pulsed ion accelerator configured in double-pulse formation mode with the first negative pulse (300–500 ns, 100–150 kV), followed by the second positive pulse (150 ns, 250–300 kV). To increase the effectiveness of ion beam focusing, a metal shield is installed on a grounded electrode. Investigations are performed using a strip focusing diode, a cone diode, and a spiral diode with metal shields of different constructions. We observed that the beam diameter at the focus decreases from 60 mm (without shield) to 40–42 mm (with a shield), which leads to an increase in the energy density by a factor of 1.5–2 being 4–5 J/cm2 at the focus. We analyzed different mechanisms for ion trajectories deviation from an ideal one: Coulomb repulsion due to incomplete space charge neutralization, influence of electromagnetic fields, etc. It is found that for a strip focusing diode the concentration of low-energy electrons accompanying the ion beam exceeds the concentration of ions by 1.3–1.5 times. The use of a metal shield improves the transportation properties of the ion beam by keeping neutralizing electrons within the beam volume which ensures its space charge neutralization during the transport.

The paper presets the results of a study on a self-magnetically insulated ion diode with an explosive-emission potential electrode. The experiments have been carried out using the TEMP-4M accelerator, operating in a double-pulse mode: the first negative pulse (300–500 ns, 100–150 kV) followed by the second positive pulse (150 ns, 250–300 kV). The ion beam energy density was 0.3–2.5 J/cm2; the beam was composed from carbon ions (80–85%) and protons. We studied several geometries of the diode: planar and focusing strip arrangement, annular and spiral geometries. It was shown that during the second voltage pulse, a condition of magnetic insulation in the diode gap is fulfilled (B/Bcr ≥3). Using the new spiral geometry of the diode, it was possible to increase the efficiency of ion current generation due to the suppression of the electron component of the total diode current by increasing the electron transit time in the gap. We have increased the efficiency of carbon ion generation from 5–9% (in the planar strip diodes) up to 17–20% in the spiral diode. The spiral geometry of the diode makes it possible to increase the efficiency of C+ ion generation 25–30 times compared to the space-charge-limited current (Childe-Langmuir limit). This is more than two times higher than in other known geometries of self-magnetically insulated diodes. The spiral diode has a resource of more than 107 pulses.

The measurement of very narrow high density plasma blocks of high ion energy from targets irradiated with ps-TW laser pulses based on a new skin depth interaction process is an ideal tool for application of ion implantation in materials, especially of silicon, GaAs, or conducting polymers, for micro-electronics as well as for low cost solar cells. A further application is for ion sources in accelerators with most specifications of many orders of magnitudes advances against classical ion sources. We report on near band gap generation of defects by implantation of ions as measured by optical absorption spectra. A further connection is given for studying the particle beam transforming of n-type semiconductors into p-type and vice versa as known from sub-threshold particle beams. The advantage consists in the use of avoiding aggressive or rare chemical materials when using the beam techniques for industrial applications.

A longitudinal compression is indispensable in a final stage of the heavy ion driver system using a particle accelerator. For the beam compression, an induction buncher applies the bunching voltage so as to make a considerable velocity tilt between the head and the tail of the beam bunch. However, the velocity tilt induces mismatch oscillation of the beam envelope due to the nonconformity between the beam particle velocity and the confinement force of the lens system. At the first step of design works for the beam transport line, the initial phase advance is decided to avoid resonance lines on the tune diagram. However, as the phase advance changes in the buncher by the velocity tilt, the beam bunch reenters in the resonance condition under certain circumstances. The transport region for avoiding the resonance condition is discussed on a phase diagram, as a function of the phase advance and the velocity tilt.