Fast 2-D soft X-ray imaging device based on micro pattern gas detector

Abstract An innovative fast system for X-ray imaging has been developed at ENEA Frascati (Italy) to be used as diagnostic of magnetic plasmas for thermonuclear fusion. It is based on a pinhole camera coupled to a Micro Pattern Gas Detector (MPGD) having a Gas Electron Multiplier (GEM) as amplifying stage. This detector (2.5 cm × 2.5 cm active area) is equipped with a 2-D read-out printed circuit board with 144 pixels (12 × 12), with an electronic channel for each pixel (charge conversion, shaping, discrimination and counting). Working in photon counting mode, in proportional regime, it is able to get X-ray images of the plasma in a selectable X-ray energy range, at very high photon fluxes (106 ph s - 1mm−2 all over the detector) and high framing rate (up to 100 kHz). It has very high dynamic range, high signal to noise ratio (statistical) and large flexibility in the optical configurations (magnification and views on the plasma). The system has been tested successfully on the Frascati Tokamak Upgrade (FTU), having central electron temperature of a few keV and density of 1020 m−3, during the summer 2001, with a one-dimensional perpendicular view of the plasma. In collaboration with ENEA, the Johns Hopkins University (JHU) and Princeton Plasma Physics (PPPL), this system has been set up and calibrated in the X-ray energy range 2–8 keV and it has been installed, with a two-dimensional tangential view, on the spherical tokamak NSTX at Princeton. Time resolved X-ray images of the NSTX plasma core have been obtained. Fast acquisitions, performed up to 50 kHz of framing rate, allow the study of the plasma evolution and its magneto-hydrodynamic instabilities, while with a slower sampling (a few kHz) the curvature of the magnetic surfaces can be measured. All these results reveal the good imaging properties of this device at high time resolution, despite of the low number of pixels, and the effectiveness of the fine controlled energy discrimination

X-VUV spectroscopic imaging with a micropattern gas detector

Abstract An innovative system which combines very fast 2D imaging capabilities with spectral resolution in the X-VUV range 0.2–8 keV has been developed at ENEA-Frascati (Italy) in collaboration with INFN-Pisa (Italy). It is based on a pinhole camera coupled to a micropattern gas detector having a gas electron multiplier as gas amplifying stage. This detector (2.5 cm×2.5 cm active area), equipped with a 2D read-out printed circuit board with 144 pixels in a square matrix geometry (12×12) has been adapted to work at low energy, as far as 0.2 keV, in various configurations. Spectra with different X-VUV laboratory sources, energy calibrations curves and detection efficiency are discussed for all the proposed configurations. Thanks to the high photon flux (10 6 ph/s mm 2 ) detected by this device, high time resolution can be obtained (framing rates up to 100 kHz). The full system has been tested on the Frascati Tokamak Upgrade in 2001 and on the National Spherical Tokamak eXperiments (NSTX) in 2002 as a possible diagnostic tool for magnetic fusion plasmas. Time-resolved 2D images are presented. These results open the way to a new X-VUV imaging technique, where the low definition (limited number of pixels) is highly compensated by the strongly enhanced contrast due to the fine and controlled energy discrimination and by the capability to get images in a selected energy range. The innovative combination of these two major characteristics, make this device a candidate for applications beyond the magnetic plasma physics field

Near term perspectives for fusion research and new contributions by the Ignitor program

The main advances made within the Ignitor program, that is aimed at investigating the physics of fusion burning plasmas near ignition, are described. In particular, the operation of the machine in the H and I regimes at the 10 MA plasma current levels has been considered and analyzed. The unique properties of the plasmas that can be generated by operating the machine with reduced parameters (lower magnetic fields and plasma currents) relative to those needed to achieve ignition are identified. A key feature of this operation is the relatively fast duty cycle that can be maintained. The Ideal Ignition Conditions, under which the density barrier due to bremsstrahlung emission in high density plasmas is removed, can be attained in this case. The plasma heating cycles are identified for which the contribution of ICRH is used both to enter the H-regime and to optimize the time needed for ignition. The on going effort to set up a test ICRH facility is described. The initial results (2 km/sec) of the high speed pellet injection system developed for Ignitor and operated at Oak Ridge are reported. The combined structural analysis and integration of the entire machine core (Load Assembly) is discussed. The adopted control system for both the machine and the plasma column has been designed and is described. The design solutions of the vertical field coils made of MgB2 and operating at 10 K have been identified and the relevant R&D program is underway. The analysis of the Caorso site and of its facility for the operation of the Ignitor with approved safety standards is completed. The relevant results are being made available for the operation of Ignitor at the Triniti site within the framework of the Italy-Russia agreement on the joint construction and operation of the Ignitor facility. A development effort concerning the advanced diagnostic systems that is being carried out for fusion burning plasma regimes is described. An initial analysis of the characteristics of a neutron source based on a system of Ignitor-like machines is reported

Clinical Management of Ectopic Pregnancy Observation, Surgery and Medical therapy

The early diagnosis of ectopic pregnancy, made before the occurrence of complications linked to an hemodinamic instability, leads to a reduction of mortality from 35.5. to 3.8 per 1000 ectopic pregnancies .When the diagnosis is made, there are di erent therapeutic options that depend on the conditions of the patient, the β-hCG levels, the dimension of the adnexal mass, the condition of emergency, the site of the ectopic pregnancy and the compliance of the patient. The management can be surgical, medical and observational. Surgery can be performed in symptomatic patients with hemodynamic instability and clinical contraindications to Methotrexate therapy. Available surgical options for tubal pregnancy are: conservative treatment (salpingotomy), intermediate surgery (partial salpingectomy), and radical treatment (salpingectomy), usually performed by laparoscopy. Medical treatment by Methotrexate can be performed in stable, asymptomatic patient, with β-hCG values ≤ 3000-5000 mIU/mL and without ultrasonographic evidence of haemoperitoneum or fetal cardiac activity. Methotrexate therapy can be administered locally or systemically, with a fixed multiple dose or single dose regimen. The follow up of patients undergoing medical therapy consists of β-HCG evaluation until its serum level is undetectable. The proposal of a wait-and-see attitude can be made in absence of clinical symptoms, adnexal mass less than 4 cm at ultrasonographic evaluation, endopelvic free fluid less than 50 mL, low hCG levels (≤ 2000 mU/mL) and patient compliance in accepting potential complications like tubal rupture and hemorrag

The JET high resolution bent crystal spectrometer

Submitted to Review of Scientific Instrument. Associazione EURATOM-ENEA sulla FusioneSIGLEITItal