94 research outputs found
Correlations and pair emission in the escape dynamics of ions from one-dimensional traps
We explore the non-equilibrium escape dynamics of long-range interacting ions
in one-dimensional traps. The phase space of the few ion setup and its impact
on the escape properties are studied. As a main result we show that an
instantaneous reduction of the trap's potential depth leads to the synchronized
emission of a sequence of ion pairs if the initial configurations are close to
the crystalline ionic configuration. The corresponding time-intervals of the
consecutive pair emission as well as the number of emitted pairs can be tuned
by changing the final trap depth. Correlations between the escape times and
kinetic energies of the ions are observed and analyzed.Comment: 17 pages, 9 figure
Isotope separation in plasmas by use of ion cyclotron resonance
Selective ion-cyclotron-resonance acceleration of individual K, Ne, Cl, A, and Xe isotopes has been observed in plasmas of density 109 to 1011 cm^-3. Energy discriminating probes show good resolution of accelerated species in all cases. Mass spectrometer analyses of potassium samples, collected on cooled tungsten ribbons, showed 41K to 39K abundance ratios of 4 rather than the normal value of 0.07
Establishing low-energy sequential decomposition pathways of leucine enkephalin and its N- and C-terminus fragments using multiple-resonance CID in quadrupolar ion guide
Pulsed energy storage antennas for ionospheric modification
Interesting, "new", very high peak-power pulsed radio frequency (RF)
antennas have been assembled at the HIPAS Observatory (Alaska, USA) and also
at the University of California at Los Angeles (UCLA, USA); namely, a pair
of quarter wavelength (λ/4) long cylindrical conductors separated
by a high voltage spark gap. Such a combination can radiate multi-megawatt
RF pulses whenever the spark gap fires. The antenna at HIPAS is 53m
long (λ/2) with a central pressurized SF6 spark gap. It is
mounted 5 meters (λ/21) above a ground plane. It radiates at 2.85MHz.
The two antenna halves are charged to ± high voltages by a Tesla
coil. Spark gap voltages of 0.4 MV (at the instant of spark gap closure)
give peak RF currents of ~1200A which correspond to ~14 MW peak
total radiated power, or ~56 MW of Effective Radiated Power (ERP). The
RF pulse train is initially square, decaying exponentially in time with Qs
of ~50. Two similar but smaller 80-MHz antennas were assembled at UCLA
to demonstrate their synchronization with a pulsed laser which fired the
spark gaps in the two antennas simultanoeously. These experiments show that
one can anticipate a pulsed array of laser synchronized antennas having a
coherent Effective Radiated Power (ERP)>10GW. One can even reconsider a
pulse array radiating at 1.43MHz which corresponds to the electron gyrofrequency
in the Earth's magnetic field at ~200km altitude. These
"new" pulsed high power antennas are hauntingly similar to the ones used
originally by Hertz (1857-1894) during his (1886-1889) seminal
verifications of Maxwell's (1864) theory of electrodynamics
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