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The results of time-of-flight diagnostics of the composition of high-intensity pulsed ion beams are presented. The experiments were performed on a diode of focusing and flat geometry, in the mode of self-magnetic insulation of electrons (accelerating voltage 250–300 kV, pulse duration 120 ns, ion current density 20–300 A/cm2), and a focusing diode in an external magnetic insulation mode (300 kV, 80 ns, 100–200 A/cm2). A delay in the registration of protons by 40–50 ns (on the drift path 14–16 cm) was found in the absence of a delay in the registration of heavy ions. It has been shown that this delay can be related to the deceleration of light ions during the transport from the diode to a collimated Faraday cup. This effect of spatial compression of the ion beam in the direction of the drift increases its pulse power but complicates the time-of-flight diagnostics of its composition. [ABSTRACT FROM AUTHOR]

The focused high-intensity pulsed ion beam (HIPIB) of 100 ns order pulse is generated with respect to its spatial stability in two types of magnetically insulated ion diodes (MIDs) with geometrical focusing configuration using the passive anode, i.e., insulation of electrons with an external magnetic-field and a self-magnetic field, respectively. Anode plasma formation for the ion beam generation is based on different processes in the two types of MIDs, as the surface breakdown on the polymer-coated anode operated in the unipolar pulse mode for the external-magnetic field MID and the explosive electron emission on the graphite anode in the bipolar-pulse mode for the selfmagnetic field MID. Typical energy density per pulse is in the range of 3-6 J/cm², at an accelerating voltage of 200-300 kV with a pulse duration of 120-150 ns. The spatial deviations of the HIPIB is evaluated by measuring the energy density distribution by using an infrared diagnostic method considering neutralizing during the ion beam propagation to the focal plane with a spatial resolution of 1 mm. The ion beam deviation is about ±1.5mm for the external-magnetic field MID and ±2.5mm for the self-magnetic field MID, leading to a fluctuation in the energy density of 1%-12%, and 9%-27% within a 10mm range at the focal point, respectively. It is revealed that the displacement of different parts of a beam spot occurs nonsynchronously, mainly attributable to the intrinsic diode processes of plasma generation and expansion, and ion beam extraction from the anode-cathode gap, while the influence of magnetic field in the transportation region is negligible. The ion beam spatial deviation has a major influence on the shot-to-shot stability of ion beam, and it is suggested that the stability can be enhanced via diode process improvement. [ABSTRACT FROM AUTHOR]

High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation. [ABSTRACT FROM AUTHOR]

Abstrac: t—The results of studying the influence of radiation defects on the error of measuring the total energy of a high-intensity pulsed ion beam and its cross-sectional distribution using the thermal-imaging diagnostics (TID) are presented. The investigations were carried out at the TEMP-6 accelerator (200–250 kV, 120 ns) during operation of an ion diode in the mode of self-magnetic insulation of electrons. The ion beam consisted of С+ carbon ions (85%) and protons; the energy density at the focus was 1–5 J/cm2. It was found that when targets of different metals (titanium, stainless steel, and copper) are used, the readings of the TID differed by 40–60% for the energy-density instability in a pulse train (for a single target) of at most 10%. The causes of errors in the energy-density measurements were analyzed. It is shown that when a metal target is irradiated with a powerful ion beam, a significant number of radiation defects are formed in it. The ion-energy losses on their formation are proportional to the initial thermal energy in the target after its irradiation with the ion beam and have values of 22% in stainless steel, 30% in copper, and 70% in titanium targets. When the ion-energy loss on the formation of radiation defects is taken into account, the error of the TID technique does not exceed 15% when using targets of different metals. [ABSTRACT FROM AUTHOR]