APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

13 Feb 2012

Volume 100, Issue 7, Articles (07xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 073501 (2012); http://dx.doi.org/10.1063/1.3682479 (3 pages)

S. Tongay, M. Lemaitre, J. Fridmann, A. F. Hebard, B. P. Gila, and B. R. Appleton
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Quasimonoenergetic electron beams from laser wakefield acceleration in pure nitrogen

M. Z. Mo, A. Ali, S. Fourmaux, P. Lassonde, J. C. Kieffer, and R. Fedosejevs

Appl. Phys. Lett. 100, 074101 (2012); http://dx.doi.org/10.1063/1.3685464 (3 pages) | Cited 3 times

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Quasimonoenergetic electron beams with maximum energy >0.5 GeV and 2 mrad divergence have been generated in pure nitrogen gas via wakefield acceleration with 80 TW, 30 fs laser pulses. Long low energy tail features were typically observed due to continuous ionization injection. The measured peak electron energy decreased with the plasma density, agreeing with the predicted scaling for electrons. The experiments showed a threshold electron density of 3×1018cm-3 for self-trapping. Our experiments suggest that pure Nitrogen is a potential candidate gas to achieve GeV monoenergetic electrons using the ionization induced injection scheme for laser wakefield acceleration.
Show PACS
52.38.Kd Laser-plasma acceleration of electrons and ions
52.59.Ye Plasma devices for generation of coherent radiation
41.75.Jv Laser-driven acceleration
41.75.Ht Relativistic electron and positron beams
29.20.Ej Linear accelerators
29.25.Bx Electron sources

Slip boundary for fluid flow at rough solid surfaces

Yongping Chen, Chengbin Zhang, Mingheng Shi, and George P. Peterson

Appl. Phys. Lett. 100, 074102 (2012); http://dx.doi.org/10.1063/1.3685490 (4 pages) | Cited 1 time

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A molecular dynamics simulation of slip boundary for fluid flow past a solid surface incorporating roughness effect as characterized by fractal geometry has been conducted with a focus on the origin of slip, fluid structure, and slip boundary flow. The results indicate that interfacial slip develops provided that the wall is effectively uncorrugated. Compared with the atomically smooth surface, extra viscous dissipation is induced for shear flow past a rough surface and leading to a reduction in boundary slip. In particular, we find that a more irregular topography decreases the boundary slip even for the same statistical roughness height.
Show PACS
47.45.Gx Slip flows and accommodation
47.15.Cb Laminar boundary layers
47.11.Mn Molecular dynamics methods

A snapshot of electrified nanodroplets undergoing Coulomb fission

Steve Arscott, Cédric Descatoire, Lionel Buchaillot, and Alison E. Ashcroft

Appl. Phys. Lett. 100, 074103 (2012); http://dx.doi.org/10.1063/1.3684979 (4 pages)

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the size distribution of electrically charged nanodroplets using atomic force microscopy (AFM). The droplets were generated using nano- and micro-scale silicon tips. A brief voltage pulse results in a “snapshot” of charged nanodroplets on a Cr surface. AFM of the traces left by the nanodroplets revealed that certain droplet diameters are favored suggesting droplet fission due to Rayleigh instability at nanometer length scales. The most occurring droplet diameters are 85.9(4.1) nm and 167.1 nm (9.7 nm) for nano- and micro-scale tips, respectively.
Show PACS
47.55.D- Drops and bubbles
47.20.Ma Interfacial instabilities (e.g., Rayleigh-Taylor)
47.65.-d Magnetohydrodynamics and electrohydrodynamics

Influence of the renormalization plasma screening on the electron-atom collision in partially ionized plasmas

Woo-Pyo Hong and Young-Dae Jung

Appl. Phys. Lett. 100, 074104 (2012); http://dx.doi.org/10.1063/1.3685495 (4 pages) | Cited 2 times

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The renormalization plasma screening effects on the elastic electron-atom collision are investigated in partially ionized dense hydrogen plasmas using the eikonal method. It is found that the renormalization plasma screening suppresses the eikonal phase shift and cross section for the elastic electron-atom collision in partially ionized plasmas. It is also found that the renormalization plasma screening effect on the elastic electron-atom collision process increases with an increasing impact parameter. In addition, it is found that the maximum position of the differential cross section is receded from the center of the atom with an increase of the Debye length.
Show PACS
52.20.Fs Electron collisions
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
34.80.Bm Elastic scattering

Influence of laser irradiated spot size on energetic electron injection and proton acceleration in foil targets

M. Coury, D. C. Carroll, A. P. L. Robinson, X. H. Yuan, C. M. Brenner, M. Burza, R. J. Gray, M. N. Quinn, K. L. Lancaster, Y. T. Li, X. X. Lin, O. Tresca, C.-G. Wahlström, D. Neely, and P. McKenna

Appl. Phys. Lett. 100, 074105 (2012); http://dx.doi.org/10.1063/1.3685615 (4 pages)

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The influence of irradiated spot size on laser energy coupling to electrons, and subsequently to protons, in the interaction of intense laser pulses with foil targets is investigated experimentally. Proton acceleration is characterized for laser intensities ranging from 2×1018-6×1020 W/cm2, by (1) variation of the laser energy for a fixed irradiated spot size, and (2) by variation of the spot size for a fixed energy. At a given laser pulse intensity, the maximum proton energy is higher under defocus illumination compared to tight focus and the results are explained in terms of geometrical changes to the hot electron injection.
Show PACS
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
13.66.Lm Processes in other lepton-lepton interactions
13.60.-r Photon and charged-lepton interactions with hadrons

Trapping and collection of uniform size droplets for nanoparticle synthesis

I. Doh, E. Y. Erdem, and A. P. Pisano

Appl. Phys. Lett. 100, 074106 (2012); http://dx.doi.org/10.1063/1.3685695 (3 pages) | Cited 1 time

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper presents a simple and fast method for droplet trapping and collection and demonstrates nanoparticle synthesis inside these trapped droplets. Since droplet trapping is size-dependent, droplets having various sizes caused by unstable inlet flows can be eliminated. Moreover, the new droplet substitutes the previous one, so we can keep the up-to-date contents of droplets at all times. All trapped droplets can be simply collected at the outlet. We had demonstrated the synthesis of iron oxide nanoparticles inside droplets and collection of them from the device. Due to its simplicity and high efficiency for selective trapping and collection, this method can become one of the key essentials in droplet-based microfluidic assays.
Show PACS
81.07.Bc Nanocrystalline materials

Profile of the liquid film wetting a channel

J. Emile, F. Casanova, H. Tabuteau, and O. Emile

Appl. Phys. Lett. 100, 074107 (2012); http://dx.doi.org/10.1063/1.3685696 (3 pages) | Cited 2 times

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a simple optical technique to investigate the characteristics of liquid films wetting solid surfaces. To validate this technique, we have studied the wetting film that separates a train of lamellas moving through a channel. Total reflection of the laser beam on the wetting film/air interface is used to extract the profile and the thickness of the wetting film. For quasistatic movement of lamellas, we show that the thickness is well described by a capillary number power law.
Show PACS
68.15.+e Liquid thin films
81.70.Fy Nondestructive testing: optical methods
47.15.gm Thin film flows
68.08.Bc Wetting

Rotating turkeys and self-commutating artificial muscle motors

Benjamin M. O’Brien, Thomas G. McKay, Todd A. Gisby, and Iain A. Anderson

Appl. Phys. Lett. 100, 074108 (2012); http://dx.doi.org/10.1063/1.3685708 (3 pages) | Cited 6 times

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electrostatic motors—first used by Benjamin Franklin to rotisserie a turkey—are making a comeback in the form of high energy density dielectric elastomer artificial muscles. We present a self-commutated artificial muscle motor that uses dielectric elastomer switches in the place of bulky external electronics. The motor simply requires a DC input voltage to rotate a shaft (0.73 Nm/kg, 0.24 Hz) and is a step away from hard metallic electromagnetic motors towards a soft, light, and printable future.
Show PACS
87.85.-d Biomedical engineering
07.07.Tw Servo and control equipment; robots
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.32.Dd Connectors, relays, and switches
84.50.+d Electric motors

Influence of the dynamic plasma shielding on the elastic electron-ion collision in turbulent plasmas

Young-Dae Jung

Appl. Phys. Lett. 100, 074109 (2012); http://dx.doi.org/10.1063/1.3687188 (4 pages)

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dynamic plasma shielding effects on the elastic electron-ion collision are investigated in turbulent plasmas using the second-order eikonal method. The results show that the dynamic screening effect strongly enhances the eikonal phase shift as well as the cross section. It is also found that the dynamic screening effect decreases with increasing impact parameter. In addition, the influence of the turbulence suppresses the eikonal phase shift and cross section, especially, for small impact parameters. Moreover, it is found that the dynamic screening effect on the eikonal cross section increases with decreasing thermal energy for large impact parameters.
Show PACS
52.20.Fs Electron collisions
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
52.35.Ra Plasma turbulence

Material dependence of Casimir forces: Gradient expansion beyond proximity

Giuseppe Bimonte, Thorsten Emig, and Mehran Kardar

Appl. Phys. Lett. 100, 074110 (2012); http://dx.doi.org/10.1063/1.3686903 (4 pages) | Cited 10 times

Online Publication Date: 17 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A widely used method for estimating Casimir interactions [H. B. G. Casimir, Proc. K. Ned. Akad. Wet. 51, 793 (1948)] between gently curved material surfaces at short distances is the proximity force approximation (PFA). While this approximation is asymptotically exact at vanishing separations, quantifying corrections to PFA has been notoriously difficult. Here, we use a derivative expansion to compute the leading curvature correction to PFA for metals (gold) at room temperature. We derive an explicit expression for the amplitude math1 of the PFA correction to the force gradient for axially symmetric surfaces. In the non-retarded limit, the corrections to the Casimir free energy are found to scale logarithmically with distance. For gold, math1 has an unusually large temperature dependence.
Show PACS
65.40.-b Thermal properties of crystalline solids
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close