| 1. |
|
|
| 2. |
- Murari, A., et al.
(författare)
-
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
-
Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
|
|
| 3. |
- Stroth, U., et al.
(författare)
-
Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
-
Tidskriftsartikel (refereegranskat)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
|
|
| 4. |
- Chellaï, O., et al.
(författare)
-
Millimeter-wave beam scattering and induced broadening by plasma turbulence in the TCV tokamak
- 2021
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 61:6
-
Tidskriftsartikel (refereegranskat)abstract
- The scattering of millimeter-wave beams from electron density fluctuations and the associated beam broadening are experimentally demonstrated. Using a dedicated setup, instantaneous deflection and (de-)focusing of the beam due to density blobs on the beam path are shown to agree with full-wave simulations. The detected time-averaged wave power transmitted through the turbulent plasma is reproduced by the radiative-transfer model implemented in the WKBeam code, which predicts a ∼50% turbulence-induced broadening of the beam cross-section. The role of core turbulence for the considered geometry is highlighted.
|
|
| 5. |
- Alimena, Juliette, et al.
(författare)
-
Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider
- 2020
-
Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 47:9
-
Tidskriftsartikel (refereegranskat)abstract
- Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton-proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments-as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER-to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity 'dark showers', highlighting opportunities for expanding the LHC reach for these signals.
|
|
| 6. |
- Kersting, J., et al.
(författare)
-
Effect of Radiotherapy Dose on Outcome in Nonmetastatic Sarcoma
- 2023
-
Ingår i: Advances in Radiation Oncology. ; 8:4
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Radiation therapy (RT) is an integral part of Ewing sarcoma (EwS) therapy. The Ewing 2008 protocol recommended RT doses ranging from 45 to 54 Gy. However, some patients received other doses of RT. We analyzed the effect of different RT doses on event-free survival (EFS) and overall survival (OS) in patients with EwS.Methods and Materials: The Ewing 2008 database included 528 RT-admitted patients with nonmetastatic EwS. Recommended multimodal therapy consisted of multiagent chemotherapy and local treatment consisting of surgery (S & RT group) and/or RT (RT group). EFS and OS were analyzed with uni-and multivariable Cox regression models including known prognostic factors such as age, sex, tumor volume, surgical margins, and histologic response.Results: S & RT was performed in 332 patients (62.9%), and 145 patients (27.5%) received definitive RT. Standard dose =53 Gy (d1) was admitted in 57.8%, high dose of 54 to 58 Gy (d2) in 35.5%, and very high dose > 59 Gy (d3) in 6.6% of patients. In the RT group, RT dose was d1 in 11.7%, d2 in 44.1%, and d3 in 44.1% of patients. Three-year EFS in the S & RT group was 76.6% for d1, 73.7% for d2, and 68.2% for d3 (P = .42) and in the RT group 52.9%, 62.5%, and 70.3% (P = .63), respectively. Multivariable Cox regression revealed age > 15 years (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.63-4.38) and nonradical margins (HR, 1.76; 95% CI, 1.05-2.93) for the S & RT group (sex, P = .96; histologic response, P = .07; tumor volume, P = .50; dose, P = .10) and large tumor volume (HR, 2.20; 95% CI, 1.21-4.0) for the RT group as independent factors (dose, P = .15; age, P = .08; sex, P = .40).Conclusions: In the combined local therapy modality group, treatment with higher RT dose had an effect on EFS, whereas higher dose of radiation when treated with definitive RT was associated with an increased OS. Indications for selection biases for dosage were found. Upcoming trials will assess the value of different RT doses in a randomized manner to control for potential selection bias.
|
|
| 7. |
- Suempelmann, R., et al.
(författare)
-
Perioperative fasting times in children and adolescents
- 2022
-
Ingår i: Anasthesiologie und Intensivmedizin. - : AKTIV DRUCK & VERLAG GMBH. - 0170-5334 .- 1439-0256. ; 63, s. 320-328
-
Tidskriftsartikel (refereegranskat)abstract
- The German Scientific Working Group for Paediatric Anaesthesia (Wissenschaftlicher Arbeitskreis Kinderansthesie, WAKKA) of the German Society for Anaesthesia and Intensive Care Medicine (DGAI) has updated their current recommendations on preoperative fasting in children from 2007, along with the preoperative fasting statement of the German Association of Anaesthesiologists (Berufsverband Deutscher Anasthesisten, BDA) and DGAI from 2016 in agreement with the new evidence-based European Guideline of the European Society of Anaesthesiology and Intensive Care (ESAIC) of 2022 - and transferred it into the S1 Guideline format of the Association of the Scientific. Medical Societies in Germany (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgeselischaften e. V., AWMF). This revision became necessary because recent studies had shown that optimized fasting times improved hornoeostasis and well-being of the children, while the risk of regurgitation and aspiration had not increased. On the other hand, long periods of fasting might be the cause of misbehaviour, stress, iatrogenic dehydration and catabolism. The updated S1 Guideline therefore recommends shorter fasting times of 4 hours for small, light meals and/or formula or cow's milk (still 6 hours for a full meal), 3 hours for breast milk, and 1 hour for clear fluids (6-4-3-1 Rule). In addition, the new S1 Guideline contains further recommendations for children with concomitant diseases that are of relevance to anaesthesia, for the application of ultrasound to examine the stomach content prior to the induction of anaesthesia, for postoperative fasting and the implementation of the new rules in clinical practice.
|
|
| 8. |
- Blaha, M., et al.
(författare)
-
Analysis of extracorporeal photopheresis within the frame of the WAA register
- 2021
-
Ingår i: Transfusion and apheresis science. - : Elsevier. - 1473-0502 .- 1878-1683. ; 60:5
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate safety and if extracorporeal photopheresis (ECP) may change health criteria (HC) and quality of life (QoL).Material and method: 560 patients (33 % women) were treated with ECP for a total of 13,871 procedures during a 17-years period. Mean age was 48 years (±18, range 3−81 years). Self-estimation of QoL was graded: 0 (suicidal) up to 10 (best ever) and HC: 0 (Bed ridden, ICU condition) up to 10 (athletic). Adverse events were analyzed. ANOVA and paired comparisons were performed.Results: Patients were treated due to graft versus host disease (GVHD, n = 317), skin lymphoma (n = 70), solid organ transplants (n = 47), skin diseases (n = 20) and other diseases (n = 106). Adverse events (AEs) were registered in 5.4 % of the first treatments and in 1.2 % of the subsequent procedures. Severe AEs were present in 0.04 % of all procedures. No patient died due to the procedure. Tingling and stitching were the most common AE. For those with GVHD an improvement was noticed within approximately 10 procedures of ECP in the severity stage, QoL (from a mean of 6.1 to 6.8, p < 0.002) and the HC (6.1 -> 6.4, p < 0.014) and improved further with added procedures.Conclusion: Photopheresis is an established therapy with few side effects. The present study of soft variables indicate that GVHD shows benefits upon ECP within approximately 10 procedures in regard to the severity of mainly skin GVHD, and lower baseline levels of HC and QoL.
|
|
| 9. |
|
|
| 10. |
- Grenfell, G., et al.
(författare)
-
High-heat flux ball-pen probe head in ASDEX-Upgrade
- 2022
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 93:2
-
Tidskriftsartikel (refereegranskat)abstract
- A new high heat flux ball-pen probe head installed on the midplane manipulator is currently being used in ASDEX-Upgrade (AUG). The probe was designed to withstand high heat fluxes making possible the investigation of the plasma edge under harsh conditions, such as low power H-mode. Composed of seven pins (four Langmuir probes, mounted in two Mach probe pairs, and three ball-pen probes), the new probe head allows us to measure several plasma parameters simultaneously and with high temporal resolution. A novel method to correct the sheath potential dynamically accounting for the total secondary electron emission is introduced together with applications to obtain the electron temperature and plasma potential profiles. The total secondary electron emission yield is obtained from particle in cell simulations in AUG condition and probe realistic impact angle with respect to the magnetic field. Finally, the probe capability to investigate turbulence around the separatrix of AUG is discussed.& nbsp;
|
|
