<i>In</i> <i>situ</i> observation of the tip shape of AuGe liquid alloy ion sources using a high voltage transmission electron microscope

Driesel, W.

doi:10.1116/1.588537

Cited by 46 publications

(32 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Observations by Driesel et al 11 of liquid metal ion sources show a stable cone for very low emission currents and a cone half-angle close to 49.3°as predicted by Taylor. 12 Our observations ͑Fig.…”

Section: A Liquid Surface Modelingsupporting

confidence: 55%

A method to determine the onset voltage of single and arrays of electrospray emitters

Krpoun

Shea

2008

Journal of Applied Physics

View full text Add to dashboard Cite

This paper reports on an accurate and rapid method to compute the onset voltage of a single or an array of electrospray emitters with complex geometries and on the correlation of the simulation with experimental data. This method permits the exact determination of the onset voltage based only on the surface tension of the sprayed liquid and on the emitter geometry. The approach starts by determining the voltage at which electrostatic forces and surface tension forces are equal for a sharpening conic surface at the tip of a capillary as a function of the apex radius of the liquid. By tracing the curve of this computed equilibrium voltage as a function of the apex radius, the onset voltage for a liquid surface with the Taylor half-angle of 49.3°or larger can be determined. For smaller cone half-angles the method is only applicable to ionic sprays as an approximate knowledge of the critical field for ion emission is necessary. The combination of analytical models and finite element tools used to compute the necessary parameters is described. The method is validated on a complex microelectromechanical system emitter geometry as well as on a linear array of electrospray emitters. Finally an empirical model of the behavior of the electric field near the apex of a conic surface with asymptotes at a fixed half-angle is proposed, which allows establishing a simple method for onset voltage determination.

show abstract

Section: A Liquid Surface Modelingsupporting

confidence: 55%

A method to determine the onset voltage of single and arrays of electrospray emitters

Krpoun

Shea

2008

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…Historically, LMISs have found extensive use as ion sources of high brightness in focused-ion-beam materials-processing applications [12] and, more recently, as electric propulsion (EP) thrusters via the FEEP technology mentioned previously [13][14][15]. In an LMIS or FEEP thruster, an intense electric field is created near the surface of a low-melting-temperature liquid metal, such as indium, by a downstream electrode.…”

mentioning

confidence: 99%

Regenerable Field Emission Cathode for Spacecraft Neutralization

Makela

Washeleski

King

2009

Journal of Propulsion and Power

View full text Add to dashboard Cite

This research investigates the discharge characteristics of a field emission cathode for use in electric propulsion that has the ability to be regenerated when the emitter tip becomes damaged. Emitter tip regeneration is achieved by taking advantage of Taylor cone formation from an operating liquid-metal ion source. Tip formation is accomplished by solidifying, or quenching, the ion-emitting cone to preserve the sharp protrusion so that it can then be used for electron emission. Electron emission I-V curves were taken after tips were formed by quenching the liquid-metal ion source at ion discharge currents ranging from 1 to 25 A. Fowler-Nordheim modeling was then used to estimate the emitter tip radii of each quenched liquid-metal ion source. Results of the Fowler-Nordheim modeling were promising, showing the ability to regenerate tips and to control the features of the resulting tips by varying the ion current during the quench process. The set of experiments that are reported demonstrated the regeneration process of emitter tip radii ranging from approximately 30-45 nm from a tip quenched at 2 A down to tip radii of 15-22 nm when quenched at 25 A.

show abstract

“…It was pointed out in [3,4,5,6] that the angle of incipient conic formations is close to the Taylor cone angle.…”

mentioning

confidence: 99%

“…The development of instability results in conic cusp singularities, from which the strengthened field initiates emission processes [3,4,5,6]. The description of these processes is a key problem of the electrohydrodynamics of conducting fluids with free surfaces; interest in this problem is largely caused by the practical use of liquid-metal sources of charged particles.…”

mentioning

confidence: 99%

Formation of conic cusps at the surface of liquid metal in electric field

Зубарев

2001

Jetp Lett.

View full text Add to dashboard Cite

The formation dynamics is studied for a singular profile of a surface of an ideal conducting fluid in an electric field. Self-similar solutions of electrohydrodynamic equations describing the fundamental process of formation of surface conic cusps with angles close to the Taylor cone angle 98.6 • are obtained. The behavior of physical quantities (field strength, fluid velocity, surface curvature) near the singularity is established.It is known [1, 2] that a flat boundary of liquid metal becomes unstable in a strong electric field. The development of instability results in conic cusp singularities, from which the strengthened field initiates emission processes [3,4,5,6]. The description of these processes is a key problem of the electrohydrodynamics of conducting fluids with free surfaces; interest in this problem is largely caused by the practical use of liquid-metal sources of charged particles. The progress in this field is associated with Taylor's work [7], where it was demonstrated that the surface electrostatic pressure P E for a cone with angle 98.6• depends on the distance from its axis as r −1 and, hence, can be counterbalanced by the surface pressure P S ∼ r −1 . Since the force balance is violated at the cone apex, Taylor's solution cannot be treated as the exact solution of the problem of equilibrium configuration of a charged surface of conducting fluid and only represents the possible asymptotic form at r → ∞.At the same time, it turned out that Taylor's solution nicely describes the experimentally observed surface shape before the instant of singularity formation. It was pointed out in [3,4,5,6] that the angle of incipient conic formations is close to the Taylor cone angle.What is the reason for such a coincidence? One may assume that the mechanism for the formation of conic cusps with an angle of 98.6• during a finite time is not directly associated with the static Taylor model. A high reproducibility of experimental results and a weak * Electronic address: nick@ami.uran.ru

show abstract

In situ observation of the tip shape of AuGe liquid alloy ion sources using a high voltage transmission electron microscope

Cited by 46 publications

References 15 publications

A method to determine the onset voltage of single and arrays of electrospray emitters

A method to determine the onset voltage of single and arrays of electrospray emitters

Regenerable Field Emission Cathode for Spacecraft Neutralization

Formation of conic cusps at the surface of liquid metal in electric field

Contact Info

Product

Resources

About