Scrape Off Layer (SOL) transport and filamentary characteristics in high density tokamak regimes

A detailed cross-device investigation on the role of filamentary dynamics in high density regimes has been performed within the EUROfusion framework comparing ASDEX Upgrade (AUG) and TCV tokamaks. Both devices have run density ramp experiments at different levels of plasma current, keeping toroidal field or q95 constant in order to disentangle the role of parallel connection length and the current. During the scan at constant toroidal field, in both devices SOL profiles tend to develop a clear Scrape Off Layer (SOL) density shoulder at lower edge density whenever current is reduced. The different current behavior is substantially reconciled in terms of edge density normalized to Greenwald fraction. During the scan at constant q95 AUG exhibits a similar behaviour whereas in TCV no signature of upstream profile modification has been observed at lower level of currents. The latter behaviour has been ascribed to the lack of target density roll-over. The relation between upstream density profile modification and detachment condition has been investigated. For both devices the relation between blob-size and SOL density e-folding length is found independent of the plasma current, with a clear increase of blob-size with edge density normalized to Greenwald fraction observed. ASDEX Upgrade has also explored the filamentary behaviour in H-Mode. The experiments on AUG focused on the role of neutrals, performing discharges with and without the cryogenic pumps, highlighting how large neutral pressure not only in the divertor but at the midplane is needed in order to develop a H-Mode SOL profile shoulder in AUG

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

Observation of electroweak production of Wγ with two jets in proton-proton collisions at √s = 13 TeV

A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak W$_{γjj}$ production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for W$_{γ}$ production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

PET-guided eBEACOPP treatment of advanced-stage Hodgkin lymphoma (HD18): follow-up analysis of an international, open-label, randomised, phase 3 trial

BACKGROUND: The German Hodgkin Study Group's HD18 trial established the safety and efficacy of PET-guided eBEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone in escalated doses) for the treatment of advanced-stage Hodgkin lymphoma. However, because of a protocol amendment during the enrolment period (June 1, 2011) that changed standard treatment from eight to six cycles, the results of the HD18 trial have been partially immature. We report a prespecified 5-year follow-up analysis of the completed HD18 trial. METHODS: HD18 was an international, open-label, randomised, phase 3 trial done in 301 hospitals and private practices in five European countries. Patients aged 18-60 years with newly diagnosed, advanced-stage Hodgkin lymphoma and an Eastern Cooperative Oncology Group performance status of 0-2 were recruited. After receiving an initial two cycles of eBEACOPP (1250 mg/m(2) intravenous cyclophosphamide [day 1], 35 mg/m(2) intravenous doxorubicin [day 1], 200 mg/m(2) intravenous etoposide [day 1-3], 100 mg/m(2) oral procarbazine [day 1-7], 40 mg/m(2) oral prednisone [day 1-14], 1·4 mg/m(2) intravenous vincristine [day 8], and 10 mg/m(2) intravenous bleomycin [day 8]), patients underwent a contrast-enhanced CT and PET scan (PET-2). Patients with positive PET-2 were randomly assigned to receive standard therapy (an additional six cycles of eBEACOPP; ie, eight cycles in total) or experimental therapy (an additional six cycles of eBEACOPP plus 375 mg/m(2) intravenous rituximab; ie, eight cycles in total) until June 1, 2011. After June 1, 2011, all patients with positive PET-2 were assigned to the updated standard therapy with an additional four cycles of eBEACOPP (ie, six cycles in total). Patients with negative PET-2 were randomly assigned (1:1) to receive standard therapy (an additional six cycles of eBEACOPP [ie, eight cycles in total] until June 1, 2011; an additional four cycles of eBEACOPP [ie, six cycles in total] after June 1, 2011) or experimental therapy (an additional two cycles of eBEACOPP; ie, four cycles in total). Randomisation was done centrally with the minimisation method, including a random component, stratified by centre, age, stage, international prognostic score, and sex. The primary endpoint was progression-free survival. HD18 aimed to improve 5-year progression-free survival by 15% in the PET-2-positive intention-to-treat cohort and to exclude inferiority of 6% or more in 5-year progression-free survival in the PET-2-negative per-protocol population. This study is registered with ClinicalTrials.gov, NCT00515554, and is completed. FINDINGS: Between May 14, 2008, and July 18, 2014, 2101 patients were enrolled and 1945 were assigned to a treatment group according to their PET-2 result. In the PET-2-positive cohort, with a median follow-up of 73 months (IQR 59 to 94), 5-year progression-free survival was 89·9% (95% CI 85·7 to 94·1) in 217 patients assigned to eight cycles of eBEACOPP before the protocol amendment and 87·7% (83·1 to 92·4) in 217 patients assigned to eight cycles of rituximab plus eBEACOPP (p=0·40). Among 506 patients who received six cycles of eBEACOPP after the protocol amendment, 5-year progression-free survival was 90·1% (95% CI 87·2 to 92·9), with a median follow-up of 58 months (IQR 39 to 66). In the PET-2-negative cohort, with a median follow-up of 66 months (IQR 54 to 85) in the combined pre-amendment and post-amendment groups, 5-year progression-free survival was 91·2% (95% CI 88·4 to 93·9) in 446 patients who received eight or six cycles of eBEACOPP and 93·0% (90·6 to 95·4) in 474 patients who received four cycles of eBEACOPP (difference 1·9% [95% CI -1·8 to 5·5]). In the subgroup of PET-2-negative patients randomly assigned after protocol amendment, 5-year progression-free survival was 90·9% (95% CI 86·8 to 95·1) in 202 patients assigned to receive six cycles of eBEACOPP and 91·0% (86·6 to 95·5) in 200 patients assigned to receive four cycles of eBEACOPP (difference 0·1% [-5·9 to 6·2]). INTERPRETATION: Long-term follow-up confirms the efficacy and safety of PET-2-guided eBEACOPP in patients with advanced-stage Hodgkin lymphoma. The reduction from eight to four cycles of eBEACOPP represents a benchmark in the treatment of early-responding patients, who can now be potentially cured with a short and safe treatment approach