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Ion-beam transport in space charge neutralizing discharge channels has been proposed for the final focus and chamber transport in a heavy-ion fusion reactor. A driver scenario with two-sided target illumination requires a system of two intersecting discharges to transport beams of the same charge from opposite sides towards the fusion target. In this article we report on experiments on the creation of free-standing, intersecting high-current discharge channels. The discharges are initiated in ammonia gas (NH3) in a metallic chamber by two perpendicular CO2-laser beams, which resonantly heat and subsequently rarefy the gas along the laser paths before the breakdown. These low density channels guide the discharges along the predefined paths and also around the 90° angles without any mechanical guiding structures. In this way stable X-, T-, and L-shaped discharges with currents in excess of 40 kA, at pressures of a few mbar were created with a total length of 110 cm. An 11.4 A MeV 58Ni+12 beam from the UNILA...

High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore they are considered as an interesting alternative for the final focus and beam transport in a heavy ion beam fusion reactor. At the GSI accelerator facility, 50 cm long, stable, free-standing discharge channels with currents in excess of 40 kA in 2 to 25 mbar ammonia (NH{sub 3}) gas are investigated for heavy ion beam transport studies. The discharges are initiated by a CO{sub 2} laser pulse along the channel axis before the discharge is triggered. Resonant absorption of the laser, tuned to the {nu}{sub 2} vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. This paper describes the laser-gas interaction and the discharge initiation mechanism. We report on the channel stability and evolution, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a hydrocode simulation.