Progress and challenges in the design of ITER's polarimetric Thomson scattering diagnostic system.

Polarimetric Thomson scattering (PTS) is a technique that allows for accurate measurements of electron temperature (Te) in very hot plasmas (Te > 10 keV, a condition expected to be regularly achieved in ITER). Under such conditions, the spectral region spanned by the TS spectrum is large and extends to low wavelengths, where the transmission of the collection optics decreases, available detectors are less efficient, and the high level of plasma background light perturbs the measurements. This work presents the recent developments in the design of a PTS system for ITER, along with the challenges posed by the complex machine design. The system performance is assessed for an updated geometry (with respect to previous publication), showing that, with a scattering angle θscat = 167°, the expected signal is strongly reduced. Potential alternatives are analyzed: (1) a system employing a different laser injection position, allowing for a more favorable scattering angle and (2) a recently proposed dual-polarization laser pulse technique. The latter is evaluated for the possible ITER geometry, again showing that a more favorable scattering angle is needed for a robust performance.

Improved accuracy and robustness of electron density profiles from JET's X-mode frequency-modulated continuous-wave reflectometers.

JET's frequency-modulated continuous wave (FMCW) reflectometers have been operating well with the current design since 2005, and density profiles have been automatically calculated intershot since then. However, the calculated profiles had long suffered from several shortcomings: poor agreement with other diagnostics, sometimes inappropriately moving radially by several centimeters, elevated levels of radial jitter, and persistent wriggles (strong unphysical oscillations). In this research, several techniques are applied to the reflectometry data analysis, and the shortcomings are significantly improved. Starting with improving the equilibrium reconstruction that estimates the background magnetic field, adding a ripple correction in the reconstructed magnetic field profile, and adding new inner-wall reflection positions estimated through ray-tracing, these changes not only improve the agreement of reconstructed profiles to other diagnostics but also solve density profile wriggles that were present during band transitions. Other smaller but also persistent wriggles were also suppressed by applying a localized correction to the measured beat frequency where persistent oscillations are present. Finally, the burst analysis method, as introduced by Varela et al. [Nucl. Fusion 46 S693 (2006)], has been implemented to extract the beat frequency from stacked spectrograms. Due to the strong suppression of spurious reflections, the radial jitter that sometimes would span several centimeters has been strongly reduced. The stacking of spectrograms has also been shown to be very useful for stacking recurring events, like small gas puff modulations, and extracting transport coefficients that would otherwise be below the noise level.

Conceptual study of energy resolved x-ray measurement and electron temperature reconstruction on ITER with low voltage ionization chambers.

In tokamaks with tungsten-based plasma facing components, such as ITER, pollution of the plasma by heavy impurities is a major concern as it can lead to radiative breakdown. The radiation emitted by such impurities is mainly composed of x-rays in the [0.1; 100] keV range. A diagnostic allowing for the reconstruction of the impurity distribution is of high interest. The ITER requirements for the x-ray measurement system make it mandatory for the detector to provide spectral information. Due to the radiation environment during the ITER nuclear phase, advanced detectors exhibiting high resilience to neutrons and gamma rays, such as gas-filled detectors, are required. The use of Low Voltage Ionization Chambers (LVICs) for this purpose is investigated in this paper. Several anodes have been added to the detector in order to allow for spectral deconvolution. This article presents a conceptual study of the use of a multi-anode LVIC for energy resolved x-ray measurement on ITER. It covers the design of the multi-anode LVIC and its modeling, the method for spectral deconvolution, and its application to energy resolved x-ray tomography, as well as the computation of the electron temperature from the reconstructed local x-ray emissivity.

Observation of confined current ribbon in JET plasmas.

We report the identification of a localized current structure inside the JET plasma. It is a field-aligned closed helical ribbon, carrying current in the same direction as the background current profile (cocurrent), rotating toroidally with the ion velocity (corotating). It appears to be located at a flat spot in the plasma pressure profile, at the top of the pedestal. The structure appears spontaneously in low density, high rotation plasmas, and can last up to 1.4 s, a time comparable to a local resistive time. It considerably delays the appearance of the first edge localized mode.

Modeling a low voltage ionization chamber based tomography system on ITER.

Soft x-ray (SXR) tomography is a key diagnostic method for impurity transport study in tokamaks since it allows for local impurity density reconstruction. The International Thermonuclear Experimental Reactor (ITER) radiative environment in deuterium-deuterium and deuterium-tritium phases will limit the choices of SXR detector technologies, and gas detectors are one of the most promising solutions. In this paper, we, thus, investigate the SXR tomography possibilities on ITER using Low Voltage Ionization Chambers (LVICs). The study contains the development of a LVIC synthetic diagnostic and its application to estimate the LVIC tomographic capabilities in an ITER D-T scenario, including the influence of LVIC parameters and noise in the measurements.

Design of a dispersion interferometer combined with a polarimeter to increase the electron density measurement reliability on ITER.

A dispersion interferometer is a reliable density measurement system and is being designed as a complementary density diagnostic on ITER. The dispersion interferometer is inherently insensitive to mechanical vibrations, and a combined polarimeter with the same line of sight can correct fringe jump errors. A proof of the principle of the CO2 laser dispersion interferometer combined with the PEM polarimeter was recently conducted, where the phase shift and the polarization angle were successfully measured simultaneously. Standard deviations of the line-average density and the polarization angle measurements over 1 s are 9 × 1016 m-2 and 0.19°, respectively, with a time constant of 100 µs. Drifts of the zero point, which determine the resolution in steady-state operation, correspond to 0.25% and 1% of the phase shift and the Faraday rotation angle expected on ITER.

Polycapillary lenses for soft x-ray transmission in ITER: Model, comparison with experiments, and potential application.

Measuring Soft X-Ray (SXR) radiation [0.1 keV; 15 keV] in tokamaks is a standard way of extracting valuable information on the particle transport and magnetohydrodynamic activity. Generally, the analysis is performed with detectors positioned close to the plasma for a direct line of sight. A burning plasma, like the ITER deuterium-tritium phase, is too harsh an environment to permit the use of such detectors in close vicinity of the machine. We have thus investigated in this article the possibility of using polycapillary lenses in ITER to transport the SXR information several meters away from the plasma in the complex port-plug geometry.

Extraskeletal mesenchymal chondrosarcoma: case report and review of the literature.

A case of extraskeletal mesenchymal chondrosarcoma in a 62-year-old woman is reported. This unusual sarcoma was localized in the right thigh (quadriceps) and treated with a combination of surgery, chemotherapy and radiotherapy. Sixty-three cases were found in the literature, with neurologic localization in 29 cases and muscular localization in 34 cases. Among clinical features, a significant difference in age at the time of diagnosis was found between the two localizations, which strongly suggests the possibility of two different types of extraskeletal mesenchymal chondrosarcoma.

Carpentier-Edwards pericardial valves in the mitral position: ten-year follow-up.

OBJECTIVE: The first generation of pericardial valves was withdrawn from the market because of a high rate of premature failure. With an original design, Carpentier-Edwards pericardial valves promised improved results. METHODS: One hundred fifty patients who underwent isolated mitral valve replacement, between July 1984 and December 1993, with Carpentier-Edwards pericardial bioprostheses in our institution were followed up. Patient mean age was 62.9 +/- 11.9 years. Operative mortality was 3.3%. All but three patients were followed up for an average of 4.7 years after operation, and total follow-up was 710 patients-years. RESULTS: At the time this article was written, over 80% of patients were in New York Heart Association class I or II. After 10 years, actuarial survival rate was 71% (confidence limit 61% to 81%). Valve-related complications included the following: six valve-related deaths (0.8% patient-year), five thromboembolic episodes (0.7% patient-year), three cases of endocarditis (0.4% patient-year), four reoperations (0.5% patient-year), and four structural valve failures with calcification and stenosis (0.5% patient-year). After 10 years, freedom from valve-related complications was 66% (confidence limit 46% to 86%), from valve-related death 94% (confidence limit 89% to 99%), from reoperation 90% (confidence limit 82% to 98%), and from valve failure 76% (confidence limit 62% to 90%). CONCLUSIONS: With a low rate of valve-related events at 10 years and a low rate of structural deterioration with no leaflet tear, this prosthesis is a reliable choice for patients over 60 years of age.

New procedure to replace the aortic valve with autologous pericardium: a clinical case.

Primary tissue failure is a major problem with pericardial or porcine heterografts, and the causes of calcification of the tissue are not yet known. The deterioration of bioprostheses may be due in part to immunologic response. Using autologous tissue is a current approach of research. We present a case of replacement of the aortic valve using an original procedure with autologous pericardium.

Carpentier-Edwards pericardial bioprosthesis in aortic or mitral position: a 12-year experience.

BACKGROUND: The first generation of pericardial valves was withdrawn from the market for a high rate of premature failure. With an original design, Carpentier-Edwards pericardial valves promised improved results. METHODS: Seven hundred eighty-seven patients who underwent isolated aortic valve replacement and 182 patients who underwent isolated mitral valve replacement between July 1984 and December 1995 with Carpentier-Edwards pericardial bioprostheses in our institution were followed up. The patients' mean age was 68.3 (aortic valve replacement, AVR) and 63.9 (mitral valve replacement, MVR) years. All but five AVR patients were followed up for an average of 4.7 years after operation, with a total follow-up of 3,624 patient-years. All patients with MVR were followed up for an average of 5.3 years after operation, with a total follow-up of 969 patient-years. RESULTS: After 12 years, actuarial survival rate is 53% for AVR and 54% for MVR. Freedom from valve-related complications for aortic versus mitral valve replacement is, respectively, 68% and 55%, freedom from valve-related death is 84% and 85%, freedom from thromboembolism 87% and 94%, and freedom from endocarditis 97% and 94%. The behavior of the aortic valve is better than that of the mitral valve: freedom from reoperation is 92% and 76%, respectively; freedom from valve failure is 94% and 78%. Age is an important factor, especially in the mitral position: freedom from valve failure is 52% in patients younger than 60 years and 100% in patients older than 60 years. CONCLUSIONS: With a low rate of valve-related events at 12 years and a low rate of structural deterioration, this prosthesis is a reliable choice for AVR and in patients over 60 years for MVR. A more durable mitral bioprosthesis is needed for patients younger than 60 years.

The last generation of pericardial valves in the aortic position: ten-year follow-up in 589 patients.

BACKGROUND: The first generation of pericardial valves has been withdrawn from the market because of excessively high rates of premature failure. With its original design, the Carpentier-Edwards pericardial valve has promised improved results. METHODS: In our institution, 589 patients underwent an isolated aortic valve replacement with a Carpentier-Edwards pericardial bioprosthesis between July 1984 and December 1993. The patients' mean age was 67.5 +/- 11.2 years, and 49% of the patients were in New York Heart Association clinical class III or IV. The operative mortality rate was 2.3% (14 of 595). All patients but 4 were followed up for an average of 4.1 years after their operation, and total follow-up was 2,408 patient-years. RESULTS: At the time of the study, more than 85% of the patients were in New York Heart Association class I or II. There were 79 late deaths. After 10 years, the actuarial survival rate was 71% +/- 7%. Nineteen patients died of valve-related causes (3 endocarditis, 7 thromboembolic complications, 1 structural failure, and 8 sudden deaths). The actuarial rate of freedom from valve-related death was 94% +/- 3% at 10 years. Valve-related complications included 23 thromboembolic episodes (0.9% per patient-year), 14 endocarditis (0.5% per patient-year), 9 reoperations (0.4% per patient-year), and 4 structural valve failures with calcification and stenosis (0.2% per patient-year). After 10 years, freedom from valve-related complications was 84% +/- 6%, from reoperation 97% +/- 2%, and from valve failure 96% +/- 4%. CONCLUSIONS: Because of its low rate of valve-related events at 10 years and low rate of structural deterioration with no leaflet tears, this prosthesis is an outstanding choice for patients who need tissue valves and for patients aged 60 years or older.

Cytogenetic studies in twelve patients with primary myelofibrosis and myeloid metaplasia.

Chromosome studies on bone marrow and/or peripheral blood cells without phytohemagglutinin were performed on 12 patients with primary myelofibrosis with myeloid meta-plasia (PMMM) between 1980 and 1984. Abnormal clones were found in six patients (50%). In five cases the abnormal clone involved the long arm of chromosome #7, two of which also had partial trisomy of chromosome #1 and trisomy of 9. Additional abnormalities involving chromosomes #3, #5, #11, #13, #15, and #21 were each found once. Review of the literature showed few studies on the cytogenetics of PMMM. No specific chromosomal pattern can be established; however, abnormalities described are nonrandom.

Localization of the ventricular preexcitation site in Wolff-Parkinson-White syndrome with Doppler tissue imaging.

PURPOSE: The objective of this study was to evaluate the ability of Doppler tissue imaging (DTI) to localize the ventricular emergence site of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome). METHODS: Thirty-three patients were studied prospectively by Doppler tissue imaging (128XP and Sequoia 256 echocardiographic systems; Acuson, Mountain View, Calif) before investigation of Wolff-Parkinson-White syndrome and after radiofrequency ablation of the accessory pathways. The normal appearance of the ventricular contractions was defined in a group of 10 control subjects. The preexcitation zone was determined as a zone of maximum acceleration in "DTI acceleration mode" or as a coded contraction zone in "DTI velocity mode," at the time of the delta wave or before the onset of the QRS complex. RESULTS: The earliest ventricular activation site was correctly localized for 12 of the 15 left-sided pathways (8 anterior or anterolateral, 2 lateral or posterolateral, 2 inferior). When wall motion abnormalities were detected in the left ventricle by DTI, the left-sided localization was confirmed by electrophysiologic exploration. For the right-sided pathways, the localization was correct in only 4 of 11 cases (3 posteroseptal and 1 anterolateral). After effective ablation in all patients, the abnormalities corresponding to the electrophysiologic data disappeared totally in only 11 of 16 patients. CONCLUSION: In the presence of Wolff-Parkinson-White syndrome, DTI localizes contraction abnormalities associated with early activation of a part of the ventricle. However, the interpretation of the images remains difficult because the normal coding of the contraction of the ventricular walls depends on the incidence for which they are investigated. This noninvasive examination seems to be an effective tool for localizing the left-sided accessory pathways of the left ventricle, in particular in the anterior, anterolateral, or inferior walls.

Twelve-year experience with the 19 mm Carpentier-Edwards pericardial aortic valve.

BACKGROUND AND AIMS OF THE STUDY: In patients with small aortic annuli, the choice of prosthesis should be based on hemodynamics and valve durability. The Carpentier-Edwards pericardial valve offers good hemodynamic performance and long-term valve durability. We reviewed our 12-year experience with 121 patients who received a 19 mm prosthesis. METHODS: A total of 121 patients (97 females, 24 males; mean age 73.2 +/- 9.4 years) underwent isolated aortic valve replacement with a 19 mm Carpentier-Edwards pericardial bioprosthesis in our institution between July 1984 and December 1995. Patients were followed up for an average of 4.84 years after surgery; total follow up was 581 patient-years (pt-yr). RESULTS: The operative mortality rate was 3.3% (4/121). At the present time, 77 patients (86%) are in NYHA class I or II with a mean gradient of 18.0 +/- 6.9 mmHg and mean effective orifice area 1.1 +/- 0.23 cm2. There were 25 late deaths. After 12 years the actuarial survival rate was 42 +/- 26%. Eight patients died of valve-related cause (one endocarditis, one structural failure, two thromboembolisms, one anticoagulant-related hemorrhage, three sudden deaths). At 12 years, the actuarial rate of freedom from valve-related death was 61 +/- 37% and from non-sudden valve-related death 88 +/- 11%. Valve-related complications included six thromboembolic episodes (1.0%/pt-yr), one endocarditis (0.17%/pt-yr), two reoperations (0.34%/pt-yr) and two structural valve failures (0.34%/pt-yr). After 12 years, freedom from reoperation was 89 +/- 11%, from valve failure 92 +/- 8%, from thromboembolic episodes 82 +/- 16% and from endocarditis 99 +/- 1%. CONCLUSION: With a low rate of structural valve failure at 12 years and a good clinical performance, the Carpentier-Edwards prosthesis is a reliable alternative for small aortic annuli.

Double valve replacement with the Carpentier-Edwards pericardial valve: 10-year results.

BACKGROUND AND AIMS OF THE STUDY: The first generation of pericardial valves was withdrawn from the market because of an excessive rate of premature failure. With an original design, the Carpentier-Edwards pericardial valve promised improved results. MATERIALS AND METHODS: From July 1984 to December 1993, 71 patients underwent double mitral and aortic valve replacement with the Carpentier-Edwards pericardial valve. Mean age was 63.4 years. 58% were male, mean clinical status was 2.9 with 71% of patients in NYHA class III or IV, 55% were in atrial fibrillation. All patients were followed for an average of 4.17 years after their operation, and total follow up was 296 patients years. RESULTS: Operative mortality was 7% (5/71). At this point of the study, 70% of patients are in clinical NYHA class I or II, 42% of patients are in atrial fibrillation and 66% receive anticoagulation treatment. We observed 19 late deaths with an actuarial survival of 58% +/- 14% at ten years. Valve-related complications include four endocarditis, four reoperations, seven anticoagulant-related hemorrhages, two structural failures, one thromboembolic episode, and one sudden death. Two patients died of valve-related causes. After 10 years, freedom from valve related death is 97% +/- 3%, from endocarditis 90% +/- 8%, from reoperation 87% +/- 10%, from thromboembolic complications 98% +/- 2%, from valve failure 93% +/- 7%, and freedom from all complications is 58% +/- 18%. No failure in patients older than 60 years was noted and no leaflet tear was observed. CONCLUSIONS: The 10-year results of this pericardial bioprosthesis make this valve an outstanding choice when a bioprosthesis is required and in patients over 60 years old.

Influence of age on valve related events with Carpentier-Edwards pericardial bioprosthesis.

UNLABELLED: Age is the most important factor for the durability of biological valves. With an original design the Carpentier-Edwards pericardial valve showed improved results at 10 years. The influence of age on valve related complications is studied with a 10 year follow up on 807 valvular replacements. METHODS: Between January 1984 and December 1993, 807 patients underwent valve replacements with a Carpentier-Edwards pericardial bioprosthesis. Patients, 193 were younger than 60 years, 284 between 60 and 70 years and 330 patients were older than 70 years. All patients but seven were followed up for an average of 4.18 years after their operation and total follow up was 3373 patient years. Patients were divided into three groups of age: group I, less than 60 years; group II, 60-70 years; group III, over 70 years. A retrospective comparison was made between age groups. RESULTS: At 11 years, valve related complications included 97 patients with 27 valve related deaths. Rates of valve related death increase with age linearized rate were 0.3, 0.6 and 1.2%, respectively. No difference was observed for rates of all valve related morbidity: 2.6, 2.4 and 3.5%, respectively. Risk of thromboembolism increased with age, linearized rates were: 0.3, 0.7 and 1.3%. Risk of deterioration and reoperation decreased with age, rates of deterioration were 0.8, 0.1 and 0%. Other valve related events had the same incidence in all groups. No statistical difference was observed between group II and group III for deteriorations and reoperations. CONCLUSIONS: The performance of the Carpentier-Edwards pericardial valve is the same at 10 years in group II and III. This study supports the clinical use of this tissue valve in patients over 60 years. The results in group I are satisfactory, nevertheless, a more durable biological valve is needed for young patients.

Pericardial valves in small aortic annuli: ten years' results.

OBJECTIVE: The first generation of pericardial valves was withdrawn from the market because of too high a rate of premature failure. With an original design, the Carpentier-Edwards pericardial valve promised improved results, especially in small sizes. METHODS: Ninety patients who underwent an isolated aortic valve replacement with a 19 mm Carpentier-Edwards pericardial bioprosthesis in our institution between July 1984 and December 1993 were followed up. The mean age was 72.2 +/- 10.1 years. Fifty percent of the patients were in NYHA clinical status III or IV. The operative mortality rate was 3.7% (3/90). All patients were followed up for an average of 4.45 years after their operation and the total follow-up was 398 patient-years. RESULTS: At this time of the study, over 80% of the patients are in NYHA class I or II. There were nine late deaths. After 10 years the actuarial survival rate was 80 +/- 12%. Three patients died of valve-related causes (1 endocarditis, 1 structural failure and 1 sudden death). The actuarial rate of freedom from valve-related death was 93 +/- 6% at 10 years. Valve-related complications included two thromboembolic episodes (0.5% patient-year), one endocarditis (0.3% patient-year), one reoperation (0.3% patient-year) and one structural valve failure with calcification and stenosis (0.3% patient-year). After 10 years, freedom from reoperation was 99 +/- 1%, from valve failure 98 +/- 2%, from thromboembolic episodes 95 +/- 4% and from endocarditis 98 +/- 2%. The mean gradient was 18.8 mmHg and mean effective orifice area 1.1 cm2. CONCLUSIONS: With a low rate of valve-related events at 10 years and a low rate of structural deterioration with no leaflet tear, this prosthesis is a reliable alternative for small aortic annuli.

The Carpentier-Edwards pericardial aortic valve: intermediate results in 420 patients.

From July 1984 to December 1991, 420 patients underwent isolated aortic valve replacement with a Carpentier-Edwards pericardial bioprosthesis in our Institution. Of the patients 71.5% were male, the mean age was 66.9 +/- 11.9 years and 48% were in NYHA clinical stage III or IV. The operative mortality rate was 2.9% (12/420). All patients but six were followed up for an average of 3.9 years after their operation and total follow-up was 1444 patient-years. At this time of the study, over 80% of the patients are in NYHA class I or II, 6% are in atrial fibrillation and 7% receive anticoagulation treatment. There were 41 late deaths. After 8 years the actuarial survival rate is 80% +/- 6%. Nine patients died of valve-related causes (three endocarditis, three thromboembolic complication, one structural failure, and two sudden deaths). The actuarial rate of freedom from valve-related death was 97% +/- 3% at 8 years. Valve-related complications included 12 thromboembolic episodes (0.8% patient-year), 7 endocarditis (0.5% patient-year), 4 anticoagulant-related complications (0.2% patient-year), 6 reoperations (0.4% patient-year) and 2 structural valve failures (0.1% patient-year). After 8 years, freedom from thromboembolic complication was 96% +/- 3%, from endocarditis 97% +/- 2%, from reoperation 98% +/- 2% and from valve failure 99% +/- 1%. There were only two structural deteriorations (calcification and stenosis) and one explanation. No leaflet tear was observed. We conclude that these intermediate results are better than those obtained with previous pericardial bioprostheses.

The Carbomedics prosthetic heart valve: four year follow-up in 100 patients.

From December 1988 to December 1991, 100 patients underwent valve replacement with a Carbomedics bileaflet valve in our institution (55 aortic valve replacements, 28 mitral valve replacements, and 17 double valve replacements). Fifty-nine percent were males. Mean age was 55.7+/-12.3 years. Fifty eight percent of patients were in NYHA Clinical status III or IV. Operative mortality was 3% (3/100). All patients but one were followed up for an average of 2.8 years after their operation and total follow-up was 280 patient years. At the time of the study, more than 80% of patients were in NYHA class I or II, 34% were in atrial fibrillation and 100% of patients received anticoagulation treatment. There were 3 late deaths. After 4 years, the actuarial survival rate was 94%+/-5%. No patients died of valve-related causes. Valve-related complications included 2 thromboembolic episodes (0.7%-patient-year), 8 anticoagulant-related complications (2% patient-year), and one reoperation (0.3% patient-year). After 4 years, freedom from thromboembolic complication was 96%+/-4%, from endocarditis was 100%, from reoperation was 99%+/-1%, and from anticoagulant-related complications was 93%+/-5%. We conclude that the 4-year results compare with other bileaflet valves. More follow-up and larger studies are mandated to give definite conclusions.