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We have commissioned a high-energy glass-laser at the Large Plasma Device (LAPD) to study the interaction of a dense laser-produced plasma with a large (17 m) magnetized plasma. First experiments with an energy of the laser blow-off an order of magnitude higher than previous work (Gekelman et al. in J. Geophys. Res. 108(A7):1281, 2003) produced large amplitude Alfvén waves (δ B ⊥ /B 0≈15%). We will discuss the potential of this facility for collisionless laboratory astrophysics experiments.

The document is an erratum for a scientific paper titled "Radiation, optical, power flow, and electrical diagnostics at the Z facility." It includes corrections to figure captions and an acknowledgment section that recognizes the contributions of individuals from various laboratories in the conception and design of several diagnostics. The authors express gratitude to editors, reviewers, and employees from Lawrence Livermore National Laboratory, Sandia National Laboratories, Los Alamos National Laboratory, and other institutions for their contributions to the research. The document also mentions the management and operation of Sandia National Laboratories by National Technology and Engineering Solutions of Sandia LLC, a subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration. [Extracted from the article]

Interferometry and two-frame schlieren imaging were used to study arc discharge evolution in a small-gap, coaxial, magnetically insulated transmission line driven by a 2-TW generator with a current pulse rise time of 70 ns. Two kinds of plasma objects were observed in experiments: plasma of arc discharges and low-density peripheral plasma. Plasma fills most of the magnetically insulated transmission line (MITL) gap in the area of the arc and produces a stripe trace of evaporated metal on the surface of electrodes. Arc discharge typically arises near the cathode. Anode plasma arises in the later stage, after which, the plasma fills the gap. A scenario of plasma evolution of the arc discharge is discussed. Low-density plasma is located in thin layers near the cathode or the anode. It plays a role in the seeding of arc discharges that grow before the closure of the gap and dissipates after the closure. Index Terms--Interferometry, magnetically insulated transmission lines, schlieren diagnostic, vacuum arc discharge.

The laser-gas interaction and the discharge initiation mechanism are presented. Resonant CO2 laser heating of low-pressure ammonia gas was applied to initiate 50 cm long, free-standing discharge channels.

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 (NH[SUB3]) in a metallic chamber by two perpendicular CO[SUB2]-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 [SUP58]Ni[SUP+12] beam from the UNILAC (Universal Linear Accelerator) linear accelerator was used to probe the line-integrated ion-optical properties of the central channel in a T-shaped discharge. [ABSTRACT FROM AUTHOR]

High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft fuer Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH[sub 3]) gas are initiated by a CO[sub 2] laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the υ[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. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge. [ABSTRACT FROM AUTHOR]

Aluminum oxide (Al2O3) plasma was generated using the Ti:Sapphire/Nd:glass laser and Z-pinch pulse-power generator at the University of Nevada, Reno, Nevada Terawatt Facility. To determine the electron temperature, we use the Boltzmann plot method for the transitions (Al III 4d 2D3/2 → 4p 2P1/2) at 451.2564 nm, (Al III 4d 2D5/2 → 4p 2P3/2) at 452.9194 nm, (Al III 4p 2P3/2 → 4s 2S1/2) at 569.6603, and (Al III 4p 2P1/2 → 4s 2S1/2) at 572.2728 nm. Simultaneously, Mach–Zehnder laser interferometry was used to measure the electron number density. We compared simulated spectra obtained from PrismSPECT with electron number density and temperature measurements, and the electron temperature was found to range from 1.8 to 2.8 eV, while the electron number density was found to range from 2.3 × 1017 to 6.9 × 1017 cm−3 early in the pinched plasma formation. [ABSTRACT FROM AUTHOR]