The COMPASS tokamak (
R
= 0.56 m,
a
= 0.2 m,
B
T
= 1.3 T,
I
p
~ 300 kA, pulse duration 0.4 s) operates in ITER-like plasma shape in H-mode with Type-I ELMs. In 2019, we plan to install into the ...divertor a test target based on capillary porous system filled with liquid lithium/tin. This single target will be inclined toroidally in order to be exposed to ITER-relevant surface heat flux (20 MW/m
2
). Based on precisely measured actual heat fluxes, our simulations predict (for 45° inclination, without accounting for the lithium vapor shielding) the surface temperature rises up to 700°C within 120 ms of the standard ELMy H-mode heat flux with ELM filaments reaching hundreds MW/m
2
. Significant lithium vaporization is expected. The target surface will be observed by spectroscopy, fast visible and infrared cameras. The scientific program will be focused on operational issues (redeposition of the evaporated metal, ejection of droplets, if any) as well as on the effect on the plasma physics (improvement of plasma confinement, L–H power threshold,
Z
eff
, etc.). After 2024, a closed liquid divertor may be installed into the planned COMPASS Upgrade tokamak (
R
= 0.84 m,
a
= 0.3 m,
B
T
= 5
T
,
I
p
= 2 MA,
P
in
= 8 MW, pulse duration ~2 s) with ITER-relevant heat fluxes loading the entire toroidal divertor.
For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of a runaway beam, it is important to obtain the runaway electrons after the disruption. In ...this paper we report on the first discharges achieved with a post-disruptive runaway electron beam, termed a ‘runaway plateau’, in the COMPASS tokamak. The runaway plateau is produced by a massive gas injection of argon. Almost all of the disruptions with runaway electron plateaus occurred during the plasma current ramp-up phase. The Ar injection discharges with and without a runaway plateau were compared for various parameters. Parametrisation of the discharges shows that the COMPASS disruptions fulfil the range of parameters important for runaway plateau occurrence. These parameters include electron density, electric field, disruption speed, effective safety factor, and the maximum current quench electric field. In addition to these typical parameters, the plasma current value just before the massive gas injection proved to be surprisingly important.
Laššuthová P, Mazanec R, Vondráček P, Šišková D, Haberlová J, Sabová J, Seeman P. High frequency of SH3TC2 mutations in Czech HMSN I patients.
Charcot–Marie–Tooth (CMT) neuropathy type 4C (CMT4C) is ...an autosomal recessive (AR), demyelinating neuropathy with early spine deformities caused by mutations in the SH3TC2 gene. To determine the spectrum of SH3TC2 mutations in the Czech population, the entire coding region of SH3TC2 was sequenced in 60 unrelated Czech patients. The prevalent mutation was shown to be the p.Arg954Stop. Therefore, 412 additional patients referred for CMT testing were tested for the presence of p.Arg954Stop only. Of 60 patients in whom the SH3TC2 gene was sequenced, at least one mutation was detected in 13 (21.7%) patients and biallelic pathogenic mutations were detected in 7 (11.6%) patients. Of the 412 patients tested for p.Arg954Stop, the mutation was found in 8 patients (1.94%), 6 were homozygous and 2 were heterozygous. The second causative mutation was detected by sequencing in one of the patients but not in the other. Nine novel sequence variants were detected. Their pathogenicity was further tested in silico and in control samples. Mutations in the SH3TC2 gene are a frequent cause of demyelinating hereditary neuropathy among Czech patients. In total, at least one mutation was found in 21 unrelated patients. CMT4C seems to be the most frequent type of AR CMT and one of the most frequent of all CMT types. Mutation p.Arg954Stop is highly prevalent in the Czech population. Patients with demyelinating neuropathy along with non‐dominant mode of inheritance and negative for CMT1A/hereditary neuropathy with liability to pressure palsy should be tested for the presence of the p.Arg954Stop mutation or other mutations in the SH3TC2 gene.
The patient registries belong to the core activities which can help us in planning of the effective health care, assessing standards of diagnosis and care, and answer the questions concerning on ...epidemiologic data. Besides of the local hospital-based databases and registries we can find in Czech Republic four national registries of hereditary neuromuscular disorders associated under unique name: ReaDy (registry of muscular dystrophy). Four registries are currently running: Duchenne/Becker muscular dystrophy (DMD/BMD), spinal muscular atrophy (SMA), myotonic disorders (MD), and facioscapulohumeral muscular dystrophy (FSHD). Each registry is independent and has its own curator. The registries are under the supervision of Czech neuromuscular society. The technology, the data collection, the storage, the backup, and analyses are provided by the Institute of Biostatistics and Analyses, Masaryk University, Brno, CR. On-line data collection is based on a TRIALDB system developed on Yale University, Connecticut, USA, which is widely used for this purpose. For each patient is generated a unique ID; all data transfer is encrypted and the system is designed to prevent their unauthorized use during data transfer. Laws and regulations in CR require having an informed consent from all patients whose data are used in the registry. All claims for personal data protection were met. Data are stored on the central server on Masaryk University in Brno in Oracle 9i database. Since 2011 to the March 2014 796 Czech patients were collected: 370 DM, 277 DMD/BMD, 89 FSHD, and 60 SMA. The majority (76%) of all records are from two centers (Prague and Brno). The average annual increase during last three years is 96 patients. The biggest acquisition reveal patients with myotonic disorders (about 45 per year), the smallest growth has the registry FSHD with approx. 11 patients per annum.
This paper summarizes the status of the COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for the future studies. The former COMPASS-D tokamak was in ...operation at UKAEA Culham, UK in 1992-2002. Later, the device was transferred to the Institute of Plasma Physics of the Academy of Sciences of the Czech Republic (IPP AS CR), where it was installed during 2006-2011. Since 2012 the device has been in a full operation with Type-I and Type-III ELMy H-modes as a base scenario. This enables together with the ITER-like plasma shape and flexible NBI heating system (two injectors enabling co- or balanced injection) to perform ITER relevant studies in different parameter range to the other tokamaks (ASDEX-Upgrade, DIII-D, JET) and to contribute to the ITER scallings. In addition to the description of the device, current status and the main diagnostic equipment, the paper focuses on the characterization of the Ohmic as well as NBI-assisted H-modes. Moreover, Edge Localized Modes (ELMs) are categorized based on their frequency dependence on power density flowing across separatrix. The filamentary structure of ELMs is studied and the parallel heat flux in individual filaments is measured by probes on the outer mid-plane and in the divertor. The measurements are supported by observation of ELM and inter-ELM filaments by an ultra-fast camera.
•Power deposition on small leading edges is well described by the optical approximation.•Mini-SOL in front of the leading edge does not affect the deposited power.•The ion Larmor smoothing effect ...under the ambipolar assumption at the leading edge is weak.•The deposited power seems to be electron-dominated.
If the decision is made not to apply a toroidal chamfer to tungsten monoblocks at ITER divertor vertical targets, exposed leading edges will arise as a result of assembly tolerances between adjacent plasma-facing components. Then, the advantage of glancing magnetic field angles for spreading plasma heat flux on top surfaces is lost at the misaligned edges with an interaction occurring at near normal incidence, which can drive melting for the expected inter-ELM heat fluxes. A dedicated experiment has been performed on the COMPASS tokamak to thoroughly study power deposition on misaligned edges using inner-wall limited discharges on a special graphite tile presenting gaps and leading edges directly viewed by a high resolution infra-red camera. The parallel power flux deducted from the unperturbed measurement far from the gap is fully consistent with the observed temperature increase at the leading edge, respecting the power balance. All the power flowing into the gap is deposited at the leading edge and no mitigation factor is required to explain the thermal response. Particle-in-cell simulations show that the ion Larmor smoothing effect is weak and that the power deposition on misaligned edges is well described by the optical approximation because of an electron dominated regime associated with non-ambipolar parallel current flow.
This article presents a basis for the material selection of toroidal field coils of COMPASS-U, a medium size tokamak currently under construction. The main focus is given to a 0D model which produces ...temporal evolution of toroidal field coil parameters (e.g. voltage, temperature, energy) during a plasma discharge based on the specification of the coils, materials and power supply system. Linkage of these parameters, together with the design requirements of the tokamak, allows the reduction of design parameters space. The model was used for the selection of copper alloy candidate materials for the coils. Mechanical and electrical material tests and results from the model used to select material candidates are presented.
Display omitted
•Toroidal field coils provide 5T at a major radius of 0.894m for at least 1s.•0D numerical model was used in material selection process.•Electrical and mechanical tests of materials at room and cryogenic temperatures.
Abstract Limb girdle muscular dystrophies (LGMDs) represent a group of clinically and genetically heterogeneous disorders predominantly affecting shoulder and pelvic girdles. To date, 15 forms (2A-N) ...of autosomal recessive (AR) and eight forms (1A-H) of autosomal dominant LGMDs have been described. LGMD2A is the most frequent form of LGMD in many European countries, and is caused by mutations in the CAPN3 gene that encodes a muscle specific protease, calpain-3. Besides LGMD2A, we perform molecular genetic diagnostics of LGMD2I, LGMD2D, and LGMD2L caused by mutations in genes encoding fukutin-related protein (FKRP), alpha-sarcoglycan (SGCA) and anoctamin-5 (ANO5). Based on the results of clinical assessment and histopathological examination of muscle biopsies (including protein analysis using immunohistochemistry and immunoblotting), the mutational analysis of the CAPN3 , FKRP , SGCA , and ANO5 genes was performed at the mRNA level (using reverse transcription-PCR-direct sequencing) and/or at the DNA level (using PCR-direct sequencing) in a cohort of Czech patients with a preliminary diagnosis of LGMD. In total, we screened 230 unrelated patients and mutations associated with the disease were determined in 70 of them (30.4%). Mutations in the CAPN3 gene were found in 55 patients, and LGMD2A was confirmed to represent the most frequent AR LGMD in the Czech Republic. The homozygous occurence of the most common mutation in the FKRP gene (p.Leu276Ile) associated with LGMD2I was determined in eight patients. Mutations in the SGCA and ANO5 genes were detected in 5 LGMD2D and 2 LGMD2L patients, respectively. This work was funded by the project “CEITEC – Central European Institute of Technology” (CZ.1.05/1.1.00/02.0068).
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