Self-photopumped neonlike x-ray laser.

We propose a new x-ray laser mechanism that uses radiation from the strongest 3d ? 2p Ne-like resonance line in an optically thick plasma to radiatively drive population from the Ne-like ground state to the 3d state, which then lases to two 3p states. Collisional mixing of the 3p states with nearby 3s and 3d states depopulates the lower laser states. Modeling is presented for this mechanism in Ne-like Ar, and in experiments we observe one potential 3d ? 3p lasing transition at 45.

Lasing at 7.9 nm in nickellike neodymium.

Using a series of 150-ps pulses from the Nova laser to illuminate neodymium slab targets, we observe a 38-psduration lasing pulse at 7.906 nm in nickellike neodymium on the J = 0 ? 1, 4d ? 4p transition. To overcome the low gain in this system, we used a traveling-wave geometry in conjunction with two slab targets that were coupled lengthwise to increase the effective length and whose surfaces were curved to compensate partially for refraction effects.

Use of the prepulse technique to enhance the weak 18.2-nm laser line in neonlike selenium.

We report strong lasing in selenium on the neonlike 3p ? 3s, J = 0 ? 1 transition at 18.2 mn when the prepulse technique of using a low-intensity prepulse before the main optical drive pulse is used to illuminate the selenium target. Without the use of the prepulse, this line is 2 orders of magnitude weaker.

Resonantly photo-pumped Li-like x-ray lasers.

We identify potential candidates for achieving x-ray lasing in Li-like ions by utilizing Ly-alpha or He-alpha radiation to photopump an electron resonantly from the n = 2 state of the Li-like ion to the n = 4 or 5 state with subsequent lasing between the n = 5 ? n = 4, n = 5 ? n = 3, or n = 4 ? n = 3 states of the Li-like ion. To identify potential resonances we calculate all the n = 2 ? n = 4 and 5 transitions in Li-like ions that look favorable to pump and identify the resonances that are possible with Ly-alpha or He-alpha radiation. Many laser candidates are identified with the baron-pumped Na scheme being modeled as it appears to be an extremely promising candidate that could be driven by pulsed power machines or optical lasers of modest energy.

Reinvestigating the early resonantly photopumped x-ray laser schemes.

Although H and He-like resonantly photopumped laser schemes were among the earliest methods proposed for producing x-ray lasers, demonstrating these schemes in the laboratory has proved to be elusive. Nevertheless the resonantly photopumped schemes remain interesting both because of their potential to improve the efficiency of lasers that otherwise operate through other process such as recombination and because of their potential for yielding entirely new and relatively efficient lasers. We present an expanded list of candidate lasers that operate by utilizing Ly-alpha or He-alpha radiation from a pump ion to photopump an electron from the ground state of a H or He-like lasant ion to the n = 3 or 4 state, with subsequent lasing between the n = 4 ? n = 3 or n = 3 ? n = 2 states of the H or He-like ion.

Vanadium-pumped titanium x-ray laser.

A new laboratory x-ray laser is described that is resonantly photopumped by two 3d ? 2p emission lines in fluorinelike vanadium (Z = 23) and lases on several 3p ? 3s transitions in neonlike titanium (Z = 22). Calculations show that five of the laser lines have gains greater than 5 cm(-1) for reasonable values of the pump lines, with the shortest wavelength of the five being at 32.65 nm.

[Distal esophageal banding. A modified method of surgical treatment of obesity].

64 patients were treated with distal oesophageal banding for morbid obesity from 30/4-1984 to 1/6-1988. By this method a Dacron vascular prosthesis is passed around the oesophagus from incisura cardiaca to pars cardiaca. There will be no upper ventricular pouch.