Experiments on the interaction of current channels in a laboratoryplasma: relaxation to the force-free state

A series of experiments on the dynamic interaction of two current channels has been performed in the large plasma device, a laboratory device at UCLA. The two current channels are formed by coating the cathode source nonuniformly and then biasing it with respect to an anode 10 m away. The experiment consists of two phases, one in which a net current is drawn through the plasma, and one in which the net current is zero. The current channels twist about each other, merge, and evolve toward a force-free state when a net current is drawn through the plasma. When the net current is zero the interaction between the channels is greatly reduced. The dynamics of the system are dominated by electron pressure and associated electrostatic fields. However, as the currents twist, a small amount of magnetic helicity is generated. The helicity and its temporal rate of change are computed and found to compare within experimental uncertainty to the predicted rate     

A high-current electron beam ion trap as an on-line charge breeder for the high precision mass measurement TITAN experiment

The precision of atomic mass measurements in a Penning trap is directly proportional to the charge state q of the ion and, hence, can be increased by using highly charged ions (HCI). For this reason, charge breeding with an electron beam ion trap (EBIT) is employed at TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) on-line facility in Vancouver, Canada. By bombarding the injected and trapped singly charged ions with an intense beam of electrons, the charge state of the ions is rapidly increased inside the EBIT. To be compatible with the on-line requirements of short-lived isotopes, very high electron beam current densities are needed. The TITAN EBIT includes a 6 Tesla superconducting magnet and is designed to have electron beam currents and energies of up to 5 A and 60 keV, respectively. Once operational at full capacity, most species can be bred into a He-like configuration within tens of ms. Subsequently, the HCI are extracted, pass a Wien filter to reduce isobaric contamination, are cooled, and injected into a precision Penning trap for mass measurement. We will present the first results and current status of the TITAN EBIT, which has recently been moved to TRIUMF after assembly and commissioning at the Max-Planck-Institute (MPI) for Nuclear Physics in Heidelberg, Germany.     

Analyticity properties of the surface free energy of the Ising model

For an Ising ferromagnet with nearest-neighbour interactions of strengthK and surface magnetic fieldh, the surface free energy in the presence of a positively (or negatively) magnetized zero-field bulk phase is shown to be analytic inh for Reh<K–/, where =2.96 ... and is the inverse temperature. This puts the lower boundK–/ on the values ofh at which wetting and layering transitions can take place.     

Zur Kenntnis der Chemie der Metallcarbonyle und der Cyanokomplexe in flüssigem Ammoniak. XXXII. Über die Reaktionen von η5-C5H5Mo(CO)3CH3 und η5-C5H5Fe(CO)2CH3 mit flüssigem Ammoniak

The Chemistry of Metal Carbonyls and Cyano Complexes in Liquid Ammonia. XXXII. On the Reaction of η⁵-C₅H₅Mo(CO)₃CH₃ and η⁵-C₅H₅Fe(CO)₂CH₃ with Liquid Ammonia η⁵-C₅H₅Mo(CO)₃CH₃ reacts with liquid NH₃ to give η⁵-C₅H₅Mo(CO)₂(NH₃)H and acetamide: In contrast, η⁵-C₅H₅Fe(CO)₂CH₃ undergoes a carbonyl insertion to give the acetyl complex η⁵-C₅H₅Fe(CO)(NH₃)COCH₃: The NH₃ ligand in η⁵-C₅H₅Fe(CO)(NH₃)COCH₃ can be substituted by pyridine.     

Low temperature expansion for continuous-spin Ising models

We consider general ferromagnetic spin systems with finite range interactions and an even single-spin distribution of compact support on IR. It is shown under mild assumptions on the single-spin distribution that a low temperature expansion, in powers ofT, for the free energy and the correlation functions is asymptotic. We also prove exponential clustering in the pure phases and analyticity of the free energy and of the correlation functions in the reciprocal temperature for Re large.Supported in part by N.S.F. Grant No. Phy. 78-15920 and MCS 78-01885On leave from: Départment de Physique Théorique, Université de Louvin, BelgiumSupported in part by the Swiss National Foundation for Scientific Research     

The chemistry of 2H-3,1-benzoxazine-2,4(1H)dione (isatoic anhydrides) 1. The synthesis of N-substituted 2H-3,1-benzoxazine-2,4(1H)diones

Three methods for the preparation of N-substituted 2H-3,1-benzoxazine-2,4(1H)diones (isatoic anhydrides) (1) utilizing 2-chloro-, 2-nitrobenzoic acids and N-unsubstituted isatoic anhydrides as starting materials, are described.     

Zur Kenntnis der Chemie der Metallcarbonyle und der Cyanokomplexe in flüssigem Ammoniak. XXXI. Über die Reaktionen von kationischen η5-Cyclopentadienylmolybdäncarbonyl-Komplexen mit flüssigem Ammoniak

The Chemistry of Metal Carbonyls and Cyano Complexes in Liquid Ammonia. XXXI. On the Reactions of Cationic η⁵-Cyclopentadienyl-molybdenumcarbonyl Complexes with Liquid Ammonia Depending on the reaction conditions, the cationic complexes [η⁵-C₅H₅Mo(CO)₃L]⁺ (L = NH₃, PPh₃, CO) react with liquid ammonia according to: The characteristics and reactivities of the new carbomoyl derivatives are described.     

First order phase transition in the plane rotator ferromagnetic model in two dimensions

We show that the two-dimensional isotropic ferromagnetic rotator model exhibits a first order phase transition if the interaction decays asr ^– with 2<<4.Work supported by Fonds National Suisse de la Recherche Scientifique.     

Dibutylsilylene Derivatives of Tartaric Acid

Crystals of the bis(tert‐butyl)silylene (DTBS) derivatives of the tartaric acids were synthesized from D ‐, L ‐, rac‐, and meso‐tartaric acid and DTBS bis(trifluoromethanesulfonate): two polymorphs of Si₂tBu₄(L ‐Tart1,2;3,4H_–4) (L ‐ 1a and L ‐ 1b ), the mirror image of the denser modification (D ‐ 1b ) as well as the racemate ( 2 ), and the meso analogue Si₂tBu₄(meso‐Tart1,3;2,4H_–4) ( 3 ). The structures were determined by single‐crystal X‐ray diffraction. The threo‐configured D ‐ and L ‐ (and rac‐) tartrates were coordinated by two tBu₂Si units forming five‐membered chelate rings, whereas the erythro‐configured meso‐tartrate formed six‐membered chelate rings. The new compounds were analyzed by NMR techniques, including ²⁹Si NMR spectroscopy, and single‐crystal X‐ray crystallography.     

Copper‐Mediated ortho‐Nitration of (Hetero)Arenecarboxylates

Various (hetero)arenecarboxylic acids were converted to the corresponding Daugulis amides and nitrated selectively in the ortho‐position in the presence of [CuNO₃(PPh₃)₂] and AgNO₂ at 50 °C. A microwave‐assisted saponification allows regenerating the carboxylate group within minutes, which may then be removed tracelessly by protodecarboxylation, or substituted by aryl‐ or alkoxy‐groups via decarboxylative cross‐coupling.