15014169
Multi-wavelength INTEGRAL network (MINE) observations of the microquasar GRS 1915+105
We present the international collaboration MINE (Multi-lambda Integral NEtwork) aimed at conducting multi-wavelength observations of X-ray binaries and microquasars simultaneously with the INTEGRAL gamma-ray satellite. We will focus on the 2003 March-April campaign of observations of the peculiar microquasar GRS 1915+105 gathering radio, IR and X-ray data. The source was observed 3 times in the plateau state, before and after a major radio and X-ray flare. It showed strong steady optically thick radio emission corresponding to powerful compact jets resolved in the radio images, bright near-infrared emission, a strong QPO at 2.5 Hz in the X-rays and a power law dominated spectrum without cutoff in the 3-300 keV range. We compare the different observations, their multi-wavelength light curves, including JEM-X, ISGRI and SPI, and the parameters deduced from fitting the spectra obtained with these instruments on board INTEGRAL.
119428235
Simultaneous multi-wavelength observations of microquasars(the MINE collaboration)
We present the international collaboration MINE (Multi- INTEGRAL NEtwork) aimed at conducting multi- wavelength observations of microquasars simultaneously...
121075027
Performance of a high‐current metal vapor vacuum arc ion source
The operational characteristics of a metal vapor vacuum arc ion source have been studied. The beam current has been measured as a function of ion source extraction voltage (5–80 kV), arc current (50–250 A), metal‐ion species (Ti, Ta, and Pb), and extractor grid spacing (0.89 and 0.38 cm). The measured beam current ranged up to 700 mA. The parametric variation of beam current is compared to that expected from the Child–Langmuir equation and excellent agreement is found.
22135306
The Metal Vapor Vacuum ARC (MEVVA) High Current Ion Source
An ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ions are extracted. Beams of a variety of ions have been produced, ranging from lithium up to uranium. At an extraction voltage of 25 kV we've measured an ion beam current of over 1 Ampere, with over 550 ema of the beam in an emittance of 0.07 ¿ cm. mradians (normalized). The ion charge state distribution varies with cathode material and with arc power; for uranium a typical distribution is peaked at U5+, with up to 40% of the beam current in this charge state.
119284118
Primordial Magnetic Fields in Cosmology
Magnetic fields have been observed in galaxies, clusters of galaxies and probably in superclusters. While mechanisms exist to generate these in the late universe, it is possible that magnetic fields have existed since very early times. This thesis is concerned with methods to predict the form of such imprints. We review in detail a standard, linearised cosmology before introducing an electromagnetic field. We then consider the intrinsic statistics of the magnetic stresses in two ways, analytically and via static realisations. We construct the power spectra, some of which we present for the first time. At the one- and three-point level we find significant intrinsic non-Gaussianities. Finally we turn to the observable impacts a primordial magnetic field. Assuming coherence, the statistics of the source can be mapped onto the CMB in a simple manner. We demonstrate that our approach is valid by reproducing the signals for Gaussian power law fields on the microwave sky. [ABRIDGED]
55443916
Ion spectra of vacuum arc plasma with compound and alloy cathodes
We have carried out an experimental investigation of the charge state distribution of ions produced in the vacuum arc plasma for the case when the cathode is a compound or alloy. The plasma was generated in a metal vapor vacuum arc ion source, and the charge state spectra were measured using a time‐of‐flight method. We have compared these spectra to the spectra obtained from cathodes of the constituent elements. The cathode materials used and reported on here were the following groups: SiC/Si/C [i.e., we have compared the spectra obtained using a cathode of silicon carbide with the spectra obtained using (a) a silicon cathode and (b) a carbon cathode], TiC/TiN/TiO2/Ti/C, WC/W/C, (UC‐ZrC)/UN/U/Zr/C, brass/Cu/Zn, and stainless steel/Fe/Cr/Ni. The arc current employed throughout was approximately 100 A. We find that the charge state distributions change depending on the elemental composition of the alloy or compound of which the cathode is fabricated.
55929053
Vacuum-spark metal ion source based on a modified Marx generator
The plasma-generating parts of ion sources including their power supplies are usually floated to high potential (ion extraction voltage), thus requiring great insulation efforts and causing high costs for high-energy ion beams. A new concept for pulsed ion sources is presented in which a single power supply is used to simultaneously produce the plasma and high extractor voltage via a modified Marx generator. Proof-of-principle experiments have been performed with high-current spark discharges in vacuum where multiply charged ions are produced with this Marx-generator-based ion source ("Magis"). Using "Magis", it has been demonstrated that pulsed ion beams of very high energies can be obtained with relatively low voltage. For copper, ions of charge states up to 7+ have been found whose energy was 112 keV for a charging voltage of only 10 kV.