Demonstration of improved laser preheat with a cryogenically cooled magnetized liner inertial fusion platform.

We report on progress implementing and testing cryogenically cooled platforms for Magnetized Liner Inertial Fusion (MagLIF) experiments. Two cryogenically cooled experimental platforms were developed: an integrated platform fielded on the Z pulsed power generator that combines magnetization, laser preheat, and pulsed-power-driven fuel compression and a laser-only platform in a separate chamber that enables measurements of the laser preheat energy using shadowgraphy measurements. The laser-only experiments suggest that ∼89% ± 10% of the incident energy is coupled to the fuel in cooled targets across the energy range tested, significantly higher than previous warm experiments that achieved at most 67% coupling and in line with simulation predictions. The laser preheat configuration was applied to a cryogenically cooled integrated experiment that used a novel cryostat configuration that cooled the MagLIF liner from both ends. The integrated experiment, z3576, coupled 2.32 ± 0.25 kJ preheat energy to the fuel, the highest to-date, demonstrated excellent temperature control and nominal current delivery, and produced one of the highest pressure stagnations as determined by a Bayesian analysis of the data.

Development of a deuterium-ice extruder for inertial confinement fusion experiments on the Z Facility.

A deuterium-ice extruder has been developed for inertial confinement fusion experiments on the Sandia National Laboratories Z Facility. The screw-driven extruder is filled via desublimation, where a slow flow of deuterium gas enters the extruder cavity and freezes to the walls without entering the liquid phase. Ice generated in this manner is optically clear, demonstrating its high uniformity. When the extruder cavity is filled with ice, the screw is driven downward, closing off the gas-fill line. With the ice cavity isolated, further screw rotation compresses the deuterium through a nozzle, extruding a fiber. Fiber diameters ranging from 200 to 500 µm have been extruded to lengths of 1.5 feet before hitting the vacuum chamber floor. The fiber straightness improves with the nozzle length-to-diameter aspect ratio. Deuterium-ice fibers can persist in high vacuum for more than 10 min before breaking free from the nozzle. The peripheral infrastructure required for Z experimental operations is under development. An in-vacuum stepper-motor-based drive system will allow remote operation, and a translating cathode will ensure proper placement of the fiber in the powerflow hardware.

Carcinoma of the external auditory canal: an update.

This review is a continuation of the series of 35 cases of carcinoma of the external auditory canal originally reported by the senior author and colleagues. Eighteen additional cases have been evaluated and treated since 1976. Preoperative high-resolution computed tomographic scanning has replaced polytomography, and improved surgical skull base approaches have allowed for extended resections of advanced lesions. A revised classification for local and extensive lesions is presented. The prognosis for localized tumors treated by en bloc resection remains excellent, whereas prognosis for extensive lesions might be more dependent on histologic type and grade of tumor.

Long-term surgical results for congenital aural atresia.

Thirty-nine primary surgical cases for correction of congenital aural atresia were reviewed for complications and long-term hearing results. Hearing averages of 25 dB for mild atresia, 40 dB for moderate atresia, and 46 dB for severe atresia were obtained. Serviceable hearing was achieved in 64% of the cases. The two most frequent complications were stenosis and recurrent infections of the cavity and canal skin, with an incidence of 33% and 31%, respectively. Use of split-thickness instead of full-thickness skin graft was associated with fewer complications. The goal of this review is also to share the experience of the senior author in the management of this complex problem.

An evaluation of revision stapes surgery.

The expected success rate in primary stapedectomy is well documented in recent literature, but few reports have commented on the difficulties or the expected results in revision stapes surgery. Reports have dealt with different techniques, but the surgeon and the patients should be aware of the problems and risks involved in revision stapedectomy. The records of 35 patients who had undergone revision stapedectomy were analyzed to determine the following: 1. cause of failure, 2. how to avoid these difficulties, 3. hearing results, and 4. possible identifying factors which might pinpoint those patients with a high risk for sensorineural hearing loss. A review of these cases demonstrates that the results of revision stapedectomy are different than those for primary stapedectomy.

Carcinoma of the external auditory canal.

Successful management of carcinoma of the external auditory canal depends upon four factors: 1. early diagnosis is imperative if a high cure rate is to be expected; 2. correct evaluation of the extent of the malignancy; 3. adequate surgery based upon correct evaluation; and 4. postoperative radiation in certain selected cases. In this review of 35 cases, two factors were used to determine whether the disease was localized or extensive. When extension occurs inot the mastoid as deep as the middle ear cleft or into the facial nerve, it should be designated as extensive tumor. Tumors which do no go as deep as the facial nerve or involve the mucosa of the middle ear should be designated as localized tumors. In localized tumors, it is possible to perform a wide en bloc resection of the bony and cartilaginous external auditory canal including the tympanic membrane and malleus, and if necessary, including the superficial lobe of the parotid. Postoperative radiation is indicated when the pathological specimen shows unclear margins in the surgical dissection. With localized tumors, en bloc resection of the external auditory canal offers a high cure rate. In extensive lesions, an en bloc dissection removing the bulk of the tumor mass, followed by irradiation, seems to offer at least as good a prognosis as more radical surgery.

Myringoplasty in children.

This series examines the results of myringoplasty in children using the overlay technique. Controversy still surrounds the issue of proper timing of surgery on the basis of preoperative assessment of tubal function. Results of this technique in children, using contralateral ear status as the primary predictor of success, found an overall success rate of 78%. Age appears to be a significant factor because children 10 years old and younger were found to have a higher incidence of surgical failures.

The facial nerve coursing inferior to the oval window.

Congenital anomalies of the facial nerve are of great concern to the otologic surgeon. Nine cases from the literature are reviewed and three of our own are reported in which the facial nerve coursed inferior to the oval window. All cases were explored for congenital conductive hearing impairments and were accompanied by severe stapes abnormalities.