Quartz micro-balance results of pulse-resolved erosion/deposition in the JET-ILW divertor

A set of quartz crystal microbalances (QMB) was used at JET with full carbon wall to monitor mass ero- sion/deposition rates in the remote areas of the divertor. After introduction of the ITER- like wall (ILW) in JET with beryllium main wall and tungsten divertor, strong reduction of the material deposition and accompanied fuel retention was observed. Therefore the existing QMB electronics have been modified to improve the accuracy of frequency measurements by a factor of ten down to 0.1 Hz which corresponds to 1.4 ng cm −2 . The averaged deposition rates of 1.2–3 ng cm −2 s −1 and erosion rates of 5.6–8.1 ng cm −2 s −1 were observed in the inner divertor of JET -ILW with the inner strike point positions close to the bot- tom edge of vertical tile 3 and at the horizontal tile 4 respectively. The erosion with averaged rates of ≈2.1 ng cm −2 s −1 and ≈120 ng cm −2 s −1 were observed in the outer divertor for the outer strike point po- sitions at tile 5 and tile 6 respectively.EURATOM 63305

Pre-Operative Ocular Findings and Long-Term Follow-Up in a Large Cohort of Non-Syndromic Unicoronal Craniosynostosis

(1) Background: Non-syndromic unicoronal craniosynostosis (UCS) is associated with a high prevalence of ocular anomalies. Currently, the etiology of this association remains obscure, however, it is presumed to be primarily attributed to their orbital malformations and/or secondary to craniofacial surgery. We assessed pre-operative ophthalmological examinations of non-syndromic UCS patients and compared them with their postoperative outcomes and long-term follow-up.(2) Methods: A retrospective case series was conducted on medical records of patients with non-syndromic UCS at Sophia Children’s Hospital, Rotterdam. Ophthalmologic examinations were collected at different time periods: T1 (first visit), T2 (&lt;1 year after cranioplasty), and T3 (long-term follow-up at last visit). The McNemar’s test was used for statistical analysis. (3) Results: A total of 101 patients were included, for whom examinations were available at T1 and T3. Patients had a mean age of 2.8 years (±2.7) and 9.5 (±4.9) at T1 and T3, respectively. At T1, 52 patients (51.5%) were diagnosed with strabismus, and 61 patients (60.4%) at T3. Vertical strabismus increased significantly from 23 patients (22.8%) at T1 to 36 patients (35.6%) at T3 (p = 0.011). Followed by astigmatism, which increased significantly from 38 (37.6%) at T1 to 59 (58.4%) patients at T3 (p = 0.001). T1 was available in 20 patients prior to fronto-orbital advancement (FOA), therefore, a sub-analysis was conducted on these patients, which was followed shortly after FOA at T2. Prior to FOA, strabismus was present in 11 patients (55.0%) and in 12 patients (60.0%) at T2. After FOA, strabismus worsened in two patients. (4) Conclusions: This study showed the high prevalence of ocular anomalies in patients with non-syndromic UCS before and after cranioplasty and at long-term follow-up. The findings of this study show that ophthalmic and orthoptic examinations are an important part of the optimal treatment of patients with non-syndromic UCS.</p

Development of ITER relevant ICRF wall conditioning technique on European tokamaks

In future reactor-scale superconducting fusion devices such as ITER, the presence of a permanent high magnetic field will prevent the use of conventional Glow Discharge Conditioning in between shots. Therefore, only discharges fully compatible with the presence of high magnetic field can be used for the conditioning procedure. ICRF discharge has a high potential to solve this problem. The paper presents a review of the new ICRF wall conditioning technique developed on limiter tokamaks TEXTOR and TORE SUPRA and the results of the first tests on the divertor tokamaks ASDEX Upgrade and JET.У майбутніх термоядерних установках зі надпровідними магнітними системами масштабу ИТЕРа присутність постійного сильного магнітного поля буде перешкоджати використанню звичайних тліючих розрядів для підготовки вакуумних стінок між розрядами. Тому тільки розряди, що працюють при сильному магнітному полі, можуть бути використані для цих цілей. ВЧ розряди в області частот ІЦР мають великий потенціал для рішення цієї проблеми. У даній роботі представлений огляд нових ВЧ ІЦРтехнік підготовки стінок, розвитих на токамаках з лімітером TEXTOR і TORE SUPRA і результати перших іспитів на токамаках з дивертором ASDEX UPGRADE іJET.В будущих термоядерных установках с сверхпроводящими магнитными системами масштаба ИТЕРа присутствие постоянного сильного магнитного поля будет препятствовать использованию обычных тлеющих разрядов для подготовки вакуумных стенок между разрядами. Поэтому только разряды, работающие при сильном магнитном поле, могут быть использованы для этих целей. ВЧ разряды в области частот ИЦР обладают большим потенциалом для решения этой проблемы. В настоящей работе представлен обзор новых ВЧ ИЦР техник подготовки стенок , развитых на токамаках с лимитером TEXTOR и TORE SUPRA и результаты первых испытаний на токамаках с дивертором ASDEX UPGRADE и JET

New developments in ICRF antennas and non-traditional applications of HF power on TEXTOR

This paper reviews the present status of new developments in ICRF antennas, recent results on more realistic modeling of ICRF antennas using the 3-D full electromagnetic code ICANT and, finally, the latest development in the scenarios of non-traditional applications of HF power for wall conditioning

ICRF plasmas for fusion reactor applications

The ICRF plasma production technique is considered as a promising alternative tool for the following applications in the present and next generation superconducting fusion devices: (i) Wall conditioning in the presence of permanent high magnetic field; (ii) Assistance for the tokamak start-up at low inductive electric field (E₀ ~ 0.3 V/m in ITER); (iii) Target dense plasma production (ne ≥ 10¹⁹ m⁻³) in stellarators. The paper presents a review of the ICRF plasma production technique and its applications in the present-day tokamaks and stellarators. The perspective of the alternative technique applications in ITER is analyzed in the frame of 0-D plasma modeling.ВЧ-метод утворення плазми (ICRF) розглядається як перспективний альтернативний інструмент для таких застосувань у сучасних й майбутніх надпровідних термоядерних установках: (i) ВЧ-чистка стінок в присутності постійного сильного магнітного поля; (ii) Aсистування старту токамака у режимі слабого вихрового електричного поля (E₀~ 0.3 В/м в ITERі); (iii) Створення густої вихідної плазми (ne ≥ 10¹⁹ м⁻³) в стелараторах. Зроблено огляд ВЧ-метода створення плазми та його застосування у сучасних токамаках й стелараторах. В рамках моделювання 0-D плазмовим кодом проведено аналіз перспективності використання даного метода в ITERі.ВЧ-метод создания плазмы (ICRF) рассматривается как перспективный альтернативный инструмент для следующих применений в современных и будущих сверхпроводящих термоядерных установках: (i) ВЧ-чистка стенок в присутствии постоянного сильного магнитного поля; (ii) Aссистирование старту токамака в режиме слабого вихревого электрического поля (E₀ ~ 0.3 В/м в ITERе); (iii) Создание плотной исходной плазмы (ne ≥ 10¹⁹ м⁻³) в стеллараторах. Сделан обзор ВЧ-метода создания плазмы и его применений в современных токамаках и стеллараторах. В рамках моделирования 0-D плазменным кодом проведен анализ перспективности использования данного метода в ITERе

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM