J A Tanis

Transmission Of Fast Highly Charged Ions Through A Single Glass Macrocapillary

The transmission of 3 MeV protons and 16 MeV O5+ ions through a single cylindrically‐shaped insulating macrocapillary glass has been investigated in a preliminary study. The capillary had a diameter du2009=u20090.18u2009mm and length lu2009=u200914.4u2009mm, giving an aspect ratio l/du2009=u200980. The sample was mounted on a goniometer to permit precise positioning with respect to the incident beam direction. Results show that 3 MeV protons transmit through the capillary without energy loss at small tilt angles (near zero), and the 16 MeV O5+ ions show transmission through the sample also with little energy loss at the same small tilt angles and little change in their charge state (∼1%). For a larger tilt angle (=u20091.5°), appreciable losses in energy occurred for incident O5+ and the ions changed their charge state up to 7+.

Guiding of electrons and fast ions through insulating nanocapillaries

We report new measurements of the transmission and guiding of 350, 500, and 800 eV electrons through insulating polyethylene terephthalate (PET) polymer nanocapillaries. For 800 eV the onset of guiding is found to occur at a foil tilt angle of 3°, while the results for 350 and 800 eV, combined with previous results, show the direct transmission properties for incident electron energies ranging from 250–1000 eV. Also, transmission of 16 MeV O5+ ions through the same PET foil was studied. Transmitted O5+ ions were found to lose energy and change charge upon traversing the nanocapillaries.

Electron Transmission through Polycarbonate Nanocapillaries

Transmission of electrons through a polycarbonate nanocapillary foil with diameter 200 nm and aspect ratio ~ 40 has been studied at energies 500 and 1000 eV. The direct transmission of electrons was observed for both energies while onset of guiding was observed for 500 eV. Time (charge) evolution measurements were also carried out at different sample tilt angles.

Angular and time dependence of electron transmission through a macroscale tapered glass capillary

The transmission of electrons through a tapered glass capillary was observed for 500, 800 and 1000 eV incident electrons up to about ~1?. No significant energy loss was found for the sample tilt angles investigated. The guiding ability of electrons was found to decrease with increasing energy. Time evolution measurements reveal unstable transmission through the capillary consistent with sudden bursts of elastic transmissions.

Broadening of electron beams through a macroscopic glass capillary

Broadening of transmitted electron angular profiles through a single cylindrically-shaped glass capillary was studied. The broadening effects were almost two times smaller than under similar conditions for HCIs, and transmitted electrons were found to lose energy due to poor charge deposition at the capillary exit.

Molecular and dissociative ionization in 1.0-2.0 MeV/u O5+ + O2 collisions

Yields for molecular ionization and dissociation associated with specific outgoing projectile charge states have been investigated for O5+ + O2 collisions at projectile energies of 1.0, 1.5, and 2.0 MeV/u. Time-of-flight spectra for recoiling target ions were recorded in coincidence with projectiles undergoing no charge change (direct), single-electron capture, or single-electron loss. Yields of the observed recoil-ion products are compared for specific outgoing projectile charge states as a function of energy.

Energy dependence of electron transmission through a single glass capillary

The transmission of electrons through a single glass capillary with incident energies of 300, 500, 800 and 1000 eV was studied. The results reveal two distinctly different transmission characteristics depending on the tilt angle of the capillary with respect to the incident beam and the incident energy. For small tilt angles ( ~ 2.5o) the rate decreases with increasing energy. These observations suggest that fundamentally different phenomena govern the electron transmission in these two regions.

Guiding of electrons through a single glass macrocapillary

The transmission of 500 and 800 eV electrons through a single glass macrocapillary was investigated. We find that the guiding effect known from nanocapillaries is also valid for macroscopic dimensions of the order of mm in the case of electron projectiles. Transmission of electrons could be observed for capillary tilt angles up to roughly 5°.

Time evolution of electron transmission through a single glass capillary

The time dependence of electron transmission through a single glass macrocapillary made of Borosilicate was studied for incident 500 eV electrons at capillary tilt angles ? = 0? and 2?. The time evolution reveals characteristics different from those observed for ion and electron guiding through insulating nanocapillary foils. While the transmitted intensity for 0? was about 20 times greater than for 2?, in each case electron transmission increased significantly 10 to 15 minutes after switching on the beam, reached a maximum, and then decreased to an equilibrium value 45 to 50 minutes later.

Sample deterioration in electron guiding through PET nanocapillaries

Follow-up measurements for the transmission of 500 eV electrons through the same PET nanocapillary foil used in earlier work [PRA 76, 042716 (2007)] have been performed. It is found that considerable deterioration of the sample apparently occurred since the earlier work as manifested in substantial reduced transmission intensities and greater fall-off of these intensities with increasing foil tilt angle. It is postulated that surface contamination or an increase in capillary conductivity, or both, causing an inability to maintain charge in the entrance region, led to the observed sample deterioration.