First results from the implementation of the ITER diagnostic residual gas analyzer prototype at Wendelstein 7-X.

Fusion reactors and long pulse fusion experiments heavily depend on a continuous fuel cycle, which requires detailed monitoring of exhaust gases. We have used a diagnostic residual gas analyzer (DRGA) built as a prototype for ITER and integrated it on the most advanced stellarator fusion experiment, Wendelstein 7-X (W7-X). The DRGA was equipped with a sampling tube and assessed for gas time of flight sample response, effects of magnetic field on gas detection and practical aspects of use in a state of the art fusion environment. The setup was successfully commissioned and operated and was used to observe the gas composition of W7-X exhaust gases. The measured time of flight gas response was found to be in the order of a second for a 7 m sample tube. High values of magnetic field were found to affect the partial pressure readings of the DRGA and suggest that additional shielding is necessary in future experimental campaigns.

Visible spectroscopy diagnostics for tungsten source assessment in the WEST tokamak: First measurements.

The present work concerns the measurements obtained with the Tungsten (W) Environment in Steady-state Tokamak (WEST) visible spectroscopy system during the first experimental campaign. This system has been developed in the framework of the WEST project that equipped the existing Tore Supra device with a tungsten divertor in order to test actively cooled tungsten Plasma Facing Components (PFC) in view of preparing for ITER operation. The goal of this diagnostic is to measure the PFC sources and the deuterium recycling with spectral, spatial, and temporal resolution adapted to the predicted power deposition profiles on the objects observed. Three kinds of PFCs are monitored: the Ion Cyclotron Resonance Heating (ICRH) antenna and Low Hybrid Current Drive (LHCD) launcher W limiters; one of the 6 W inner bumpers; and the upper and lower W divertors. Large-aperture in-vessel actively cooled optical systems (f-number ∼ 3) were installed for each view and connected to optical fibres. A total of 240 optical fibers can be distributed on various detection systems including a fast response-time, multi-channel, filtered photodetector-based "Filterscope" system, developed by Oak Ridge National Laboratory (USA) as well as grating spectrometers optimized for multi-sightline analysis. The first WEST experimental campaign conducted in 2017 has been dedicated to plasma start-up development during which the visible spectroscopy system has provided crucial information related to the impurity content first and then impurity sources. The diagnostic setup for that first experimental campaign was limited to the inner bumper and outer limiters but was sufficient to demonstrate that the optical setup was in accordance with the specifications. The radiance calibration procedure allowed us to estimate fluxes from the main limiter of about 8 × 1018 atoms/(s m2) and to show a first W source radial profile along the outboard limiter.

Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited).

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.

Development of visible spectroscopy diagnostics for W sources assessment in WEST.

The present work concerns the development of a W sources assessment system in the framework of the tungsten-W environment in steady state tokamak project that aims at equipping the existing Tore Supra device with a tungsten divertor in order to test actively cooled tungsten Plasma Facing Components (PFCs) in view of preparing ITER operation. The goal is to assess W sources and D recycling with spectral, spatial, and temporal resolution adapted to the PFCs observed. The originality of the system is that all optical elements are installed in the vacuum vessel and compatible with steady state operation. Our system is optimized to measure radiance as low as 1016 Ph/(m2 s sr). A total of 240 optical fibers will be deployed to the detection systems such as the "Filterscope," developed by Oak Ridge National Laboratory (USA) and consisting of photomultiplier tubes and filters, or imaging spectrometers dedicated to Multiview analysis.

Probing the plasma near high power wave launchers in fusion devices for static and dynamic electric fields (invited).

An exploratory study was carried out in the long-pulse tokamak Tore Supra, to determine if electric fields in the plasma around high-power, RF wave launchers could be measured with non-intrusive, passive, optical emission spectroscopy. The focus was in particular on the use of the external electric field Stark effect. The feasibility was found to be strongly dependent on the spatial extent of the electric fields and overlap between regions of strong (>∼1 kV/cm) electric fields and regions of plasma particle recycling and plasma-induced, spectral line emission. Most amenable to the measurement was the RF electric field in edge plasma, in front of a lower hybrid heating and current drive launcher. Electric field strengths and direction, derived from fitting the acquired spectra to a model including time-dependent Stark effect and the tokamak-range magnetic field Zeeman-effect, were found to be in good agreement with full-wave modeling of the observed launcher.

Dynamic Stark spectroscopic measurements of microwave electric fields inside the plasma near a high-power antenna.

Fully dynamic Stark effect visible spectroscopy was used for the first time to directly measure the local rf electric field in the boundary plasma near a high-power antenna in high-performance, magnetically confined, fusion energy experiment. The measurement was performed in the superconducting tokamak Tore Supra, in the near field of a 1­3 MW, lower-hybrid, 3.7 GHz wave-launch antenna, and combined with modeling of neutral atom transport to estimate the local rf electric field amplitude (as low as 1­2 kV/cm) and direction in this region. The measurement was then shown to be consistent with the predicted values from a 2D full-wave propagation model. Notably the measurement confirmed that the electric field direction deviates substantially from the direction in which it is launched by the waveguides as it penetrates only a few cm radially inward into the plasma from the waveguides, consistent with the model.

Suppression of large edge-localized modes in high-confinement DIII-D plasmas with a stochastic magnetic boundary.

A stochastic magnetic boundary, produced by an applied edge resonant magnetic perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H mode transport barrier and core confinement are unaffected by the stochastic boundary, despite a threefold drop in the toroidal rotation. These results demonstrate that stochastic boundaries are compatible with H modes and may be attractive for ELM control in next-step fusion tokamaks.

Reflections: emergency radiology.

In this article, the author compares emergency radiology as it was practiced and taught from the turn of the 20th century to the middle 1970s with the way it is practiced and taught today. Many specific examples are cited. External influences serendipitously converged in the 1960s-1980s, and their effect on the evolution of emergency radiology as it is recognized today are described.

Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings.

Congenital anomalies of the inferior vena cava (IVC) and its tributaries have become more commonly recognized in asymptomatic patients. The embryogenesis of the IVC is a complex process involving the formation of several anastomoses between three paired embryonic veins. The result is numerous variations in the basic venous plan of the abdomen and pelvis. A left IVC typically ends at the left renal vein, which crosses anterior to the aorta to form a normal right-sided prerenal IVC. In double IVC, the left IVC typically ends at the left renal vein, which crosses anterior to the aorta to join the right IVC. In azygos continuation of the IVC, the prerenal IVC passes posterior to the diaphragmatic crura to enter the thorax as the azygos vein. In circumaortic left renal vein, one left renal vein crosses anterior to the aorta and another crosses posterior to the aorta. In retroaortic left renal vein, the left renal vein passes posterior to the aorta. In circumcaval ureter, the proximal ureter courses posterior to the IVC. Other anomalies include absence of the infrarenal IVC or the entire IVC. These anomalies can have significant clinical implications. Awareness of these anomalies is necessary to avoid diagnostic pitfalls.

Is cervical spine imaging indicated in gunshot wounds to the cranium?

BACKGROUND, MATERIALS AND METHODS: Because there is no consensus regarding the necessity of imaging the cervical spine of patients who sustain a gunshot wound to the cranium, the cervical spinal radiographs of 53 consecutive patients with gunshot wounds to the cranium admitted to Hermann Hospital, a Level I trauma center, from January of 1993 to January of 1996, were reviewed. RESULTS: The cervical spine radiographs of all 53 patients were negative. CONCLUSIONS: Cervical spine injury is not associated with gunshot wound to the cranium. Therefore, patient management decisions/procedures, including endotracheal intubation, should not be delayed pending cervical spine imaging.

Use of inpatient hospital services by people aged 90-99 years.

OBJECTIVE: To examine the use of inpatient hospital services by people aged 90-99 years. DESIGN: Retrospective case note review. SETTING: Flinders Medical Centre, a 516-bed university teaching hospital in Adelaide, South Australia. PATIENTS: All patients aged 90-99 years on the separation register for 1995. MAIN OUTCOME MEASURES: Patient demographic characteristics, principal diagnosis, length of hospital stay and outcome, including destination at discharge. RESULTS: In 1995, 317 separations involved 214 patients aged 90-99 years; 148 patients (69%) were admitted to hospital once, 43 (20%) twice and 23 (11%) three times or more. In 54% of separations, patients came from the community, and these were less likely to be emergency admissions (72%) than were admissions from hostels (87%) and nursing homes (93%). Patients had a wide range of acute medical and surgical problems and a median of five documented comorbidities. Patients survived to leave hospital in 290 separations (91%) and returned directly to their previous living circumstances in 212 (67%). Median hospital stay was 5.0 days, and in 25% of separations stay was one day or less. Patients admitted under the care of geriatricians had more emergency admissions (98%) and longer mean hospital stays (8.9 days) than those admitted under surgeons (69%; 5.9 days) or other physicians (66%; 5.0 days). CONCLUSION: Despite the acute nature of their illnesses and their multiple medical problems, most hospitalised nonagenarians in this study returned directly to their previous living circumstances after short hospital stays.

Noncorrelation between thoracic skeletal injuries and acute traumatic aortic tear.

It is generally accepted that the presence of thoracic skeletal injuries has a predictive value for acute traumatic aortic tear (ATAT). The purpose of this study is to objectively assess the validity of that premise. The initial chest radiographs of 548 patients who underwent aortic angiography for suspected ATAT were reviewed for thoracic skeletal injuries. The incidence of thoracic skeletal injuries was compared between patients with and without angiographically confirmed ATAT. Rib fracture is the only thoracic skeletal injury whose incidence is statistically significantly higher in patients with ATAT (36 of 62, 58.1%) than in those without (207 of 486, 42.6%) (p = 0.0209). The positive predictive value of rib fractures in evaluating ATAT, however, is 14.8%, a rate similar to the incidence of ATAT at most trauma centers, and the specificity is 57.4%. The second most common finding in patients with ATAT, the absence of thoracic skeletal injury, is not statistically significantly different between patients with ATAT (24 of 62, 38.7%) and those without (220 of 486, 45.3%) (p = 0.3279). We conclude that (1) there is no clinically relevant correlation between thoracic skeletal injuries and ATAT, and (2) selection of patients requiring thoracic aortography must be based on appropriate mechanism of injury and radiographic evidence of mediastinal hematoma.

C2-3 facet joint "pseudo-fusion": anatomic basis of a normal variant.

OBJECTIVE: To identify the anatomic basis for apparent C2-3 facet joint fusion (pseudo-fusion) on lateral cervical spine radiographs. DESIGN AND PATIENTS: The studies of 81 consecutive blunt trauma patients who had both plain radiographs and a CT scan of the upper cervical spine were reviewed. The C2-3 facet joints were evaluated on lateral cervical spine radiographs and graded "normal" (category 1), "indistinct" (category 2), or "fused" (category 3), relative to the C3-4 level. The accompanying CT scans were reviewed for the presence of fusion and the angle of orientation of the facet joints relative to the axial and coronal planes. RESULTS: In category 1 ("normal"), the C2-3 facet joints were oriented nearly parallel to the true coronal and axial plane. In category 2 ("indistinct"), both the C2-3 facet joints were oriented obliquely to the true coronal and axial planes. In category 3 ("fused"), the C2-3 facet joints were also oriented obliquely, but at a steeper angle than in category 2. Head tilt/rotation caused a change in category rating in 5 of 81 cases (6.2%). CONCLUSION: The appearance of C2-3 facet joint fusion (pseudo-fusion) on lateral cervical spine radiographs may be a normal anatomic variant. This "pseudo-fusion" is due to the oblique orientation of these facet joints relative to the X-ray beam and is usually unaffected by patient position.

Managing stress through prevention.

This article presents a practical approach to stress management in the clinical laboratory setting. While advocating a proactive approach to stress management, the underlying principle of this paper is that several well-documented human resource techniques should be more widely interpreted and implemented to serve as stress management techniques. Major sources of stress in the clinical laboratory setting are identified, and specific strategies to address these sources are discussed.

Radiologic diagnosis of traumatic occipitovertebral dissociation: 1. Normal occipitovertebral relationships on lateral radiographs of supine subjects.

OBJECTIVE: The objective of this study was to establish a reliable method of determining the normal occipitovertebral relationship seen on lateral radiographs of the cervical spine in supine subjects in order to recognize alterations of normal that characterize occipitovertebral dissociation. MATERIALS AND METHODS: We define the rostral extension of the posterior cortex of the axis body as the posterior axial line, the distance between the basion (tip of the clivus) and the posterior axial line as the basion-axial interval, and the distance between the basion and the rostral tip of the dens as the basion-dental interval. The basion-axial interval was measured on horizontal-beam lateral radiographs of the cervical spine obtained at a 40-in. (1-m) target-film distance in 400 adults who had no occipitovertebral abnormalities. The basion-dental interval was measured in 374 (94%) of the same cohort of adults in whom the superior cortex of the dens could be identified. All radiographs were obtained with the subjects supine. The excursion of the basion referable to the posterior axial line was determined on lateral flexion and extension radiographs of 25 of the same cohort of adults. The basion-axial interval only was measured on radiographs of 50 children 2-13 years old who had no occipitovertebral abnormalities. RESULTS: In 392 (98%) of the 400 adults, the basion-axial interval did not exceed 12 mm. In eight adults (2%), the basion was situated 1-4 mm posterior to the posterior axial line. The excursion of the basion in flexion and extension ranged from 0 to 10 mm, but did not exceed the 12-mm limit of normal. The basion translated posterior to the posterior axial line in six (24%) of the 25 adults in whom excursion was measured. Of the 400 adults, the basion-dental interval ranged from 2 to 15 mm (mean, 7.5 +/- 4.3 mm [2 SD]); the 95% accuracy range was 11.8 mm. In all 50 children (100%), the basion was within the normal basion-axial interval of 12 mm, and in no instance was the basion posterior to the posterior axial line. CONCLUSION: In adults, the occipitovertebral junction can be considered normal when both the basion-axial interval and basion-dental interval are 12 mm or less. In children less than 13 years old, the basion-dental interval is not reliable because of the variable age at which complete ossification and fusion of the dens occur. The normal basion-axial interval in children did not exceed 12 mm. This simple, anatomically based method of recognizing normal occipitovertebral relationships facilitates identification of occipitovertebral dissociation.