The current I to a cylindrical probe at rest in an unmagnetized plasma, with probe bias highly positive, is determined. The way I lags behind the orbital-motion-limited (OML) current, as the radius R exceeds the maximum radius for the OML regime to hold, is of interest for space-tether applications. The ratio is roughly a decreasing function of which is independent of bias, with the electron Debye length and roughly an increasing function of the temperature ratio, The dependence of current on ion energy is used to discuss the effect of probe motion through the plasma, a case applying to tethers in low orbit.
REFERENCES
1.
2.
R. D.
Estes
, E.
Lorenzini
, J. R.
Sanmartı́n
, J.
Pelaez
, M.
Martı́nez-Sanchez
, L.
Johnson
, and I.
Vas
, J. Spacecr. Rockets
37
, 205
(2000
).3.
J. R.
Sanmartı́n
and M.
Martı́nez-Sanchez
, J. Geophys. Res.
100
, 1677
(1995
).4.
J. R.
Sanmartı́n
and R. D.
Estes
, J. Geophys. Res.
102
, 14625
(1997
).5.
M.
Martı́nez-Sanchez
and J. R.
Sanmartı́n
, J. Geophys. Res.
102
, 27257
(1997
).6.
J. R.
Sanmartı́n
, M.
Martı́nez-Sanchez
, and E.
Ahedo
, J. Propul. Power
9
, 353
(1993
).7.
R. D.
Estes
, J. R.
Sanmartı́n
, and M.
Martı́nez-Sanchez
, J. Spacecr. Rockets
37
, 197
(2000
).8.
9.
10.
L. W.
Parker
and E. C.
Whipple
, Jr., Ann. Phys. (N.Y.)
44
, 126
(1967
).11.
Condition in (11b) corresponds to a minimum of (the profile tangent at point 0, when reached from above, crosses the origin in Fig. 1). The quasineutral solution has no such property reaching 0 from below, and breaks down there; use of the full Eq. (2), however, would locally round the profile with no effect beyond the immediate neighborhood of 0, which just appears as the no energy-barrier point closest to 1.
12.
Results for from our analytical approach can be compared to numerical computations by Laframboise, who considered of order unity or moderately large [National Technical Information Service Document No. 634596 (J. G. Laframboise, “Theory of spherical and cylindrical Langmuir probes in a collisionless, Maxwellian plasma at rest,” University of Toronto Institute for Aerospace Studies Report No. 100, 1966); copies may be ordered from the National Technical Information Service, Springfield, VA 22161]. Figures 42 and 50(b) in Laframboise’s work give at and the highest bias, Figs. 6 and 7 of Ref. 9 give or about 20% too low, at the same conditions. Differences are greater at still lower bias, or 15.
13.
M. J. M.
Parrot
, L. R. O.
Storey
, L. W.
Parker
, and J. G.
Laframboise
, Phys. Fluids
25
, 2388
(1982
).
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