Time-Dependent Electron Density Measurements in a Fast Theta-Pinch Discharge

Deuchars, W. M.; Kidd, D. E.; Irving, J.; Warnock, A. C. C.

doi:10.1063/1.1754283

Cited by 4 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although laser action due to Ar2+ and Ar3f has been reported (MacFarlane 1964), little is known about the conditions under which laser action due to multiply ionized argon can occur. The Z-pinch forms a convenient plasma in which rapid heating occurs and in which laser action due to Art and Ar2+ can take place (Kulagin et al 1966, Likhachev et al 1967a, b, Vasil'eva et al 1969). In the present work the properties of an argon Z-pinch discharge, in which visible and ultraviolet laser action occurs, have been studied.…”

Section: Introductionmentioning

confidence: 99%

Laser action and plasma properties of an argon Z-pinch discharge

Illingworth

1970

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

An experimental investigation of visible and ultraviolet laser action in a small argon Z-pinch plasma has been made. The effect of initial gas pressure on the peak laser output power, implosion time, time of ultraviolet laser action and axial electron density is described, and streak photographs of the discharge are presented. Laser action at 4765 Å due to Ar+ is observed in the initial stages of the discharge at pressures below 7 mtorr. Laser action at 3511 Å due to Ar2+ occurs as a short pulse at higher initial gas pressures just after the imploding current sheath reaches the axis of the discharge tube. Typically, the axial electron density at the time of peak ultraviolet laser action was found to be 1·0 × 1015 electrons cm−3, although at certain gas pressures slightly larger values were found. Large electron density gradients occur just after ultraviolet laser action.

show abstract

Section: Introductionmentioning

confidence: 99%

Laser action and plasma properties of an argon Z-pinch discharge

Illingworth

1970

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…Deuchars et al (11) were the first to apply the Buser and Kainz technique for investigating the time rate of change in density in a linear theta pinch device. Deuchars showed that the system could easily follow rapidly changing center line density and that the frequency response was governed by the detection system and not the interferometer itself.…”

Section: Alternative Interferometric Techniquesmentioning

confidence: 99%

“…The predicted 1/e particle end loss time x , was 2.26 ysec. At a 65 millitorr fill pressure N(t) varied as; N(t) = exp(41.986 -0.4057t) , (5)(6)(7)(8)(9)(10)(11) where the predicted 1/e particle end loss time was 2.47 ysec.…”

Section: Predictions From the Computer Modelmentioning

confidence: 99%

“…Since the number density profiles for t = 0 ysec and t = 2 ysec after implosion could not be determined experimentally, a functional profile which fits available data was used. It was assumed that the number density profile was Gaussian in shape, so that -Cr/r / (t)) 2 n r (t) = n a Ct)e 1/e , (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) where n ft) is the number density on-axis (i.e., r = 0 mm) at a time t, and r 1 , (t) is the value of the radius, at a time t, where the number density has decreased by a factor of 1/e from the on-axis value. This assumption of a Gaussian distribution was based on the results of other experiments CIS, 19).…”

Section: End Loss Time From Twyman-green Interferometrymentioning

confidence: 99%

“…At a 50 millitorr fill pressure, N(t) was determined to vary as; N(t) = exp(41.793 -.4903t) , (5)(6)(7)(8)(9)(10)(11)(12)(13) where t is in ysec. For 65 millitorr fill pressure NCt) was found to be Since the data for B presented in Figure 5-7 indicate that these oscillations closely approximate a damped sinusoid, Ar (t) was assumed to vary as: -a (t)t Ar (t) = Ar pmax fcinu)(t)t]e °S , (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) where Ar is a constant, (cm), the damping rate a (t) is found pmax …”

Section: End Loss Time From Analysis Of Magnetic Field Probe Datamentioning

confidence: 99%

See 2 more Smart Citations

Studies of end loss from a theta pinch using a Twyman--Green interferometer. Scientific report 77-4

Freeman¹

1977

View full text Add to dashboard Cite

The transient rate of flow of plasma from the ends of a short, high density, low temperature linear theta pinch was studied experimentally and analytically. Diagnostic devices were used to study the discharge and plasma properties; these included a Rogowski coil, a magnetic field probe and a Twyman-Green double pass interferometer which was illuminated by a 7 mW He-Ne laser. The interferometer was used to monitor the passage of fringes with respect to time at two radial positions simultaneously by the use of a photodetector consisting of two fast silicon photodiodes with supporting circuitry. One complete fringe represented a change in number density of 2.942xl0 16 cm" 3 .Compatible interpretation of the above-mentioned diagnostics allowed evaluation of the loss rate of plasma. The major uncertainty in obtaining 1/e particle end loss times from the Twyman-Green interferometric data was associated with lack of data on the density profile. Two different techniques were developed to provide estimates of the profile. These led to loss times estimates of 1.82 usee and 2.85 usee for a 50 millitorr fill pressure of H_, and 2.39 usee and 2.81 psec for a 65 millitorr fill pressure. These loss times were compared with: results obtained from magnetic field probe data on plasma column oscillation which indicated the loss rate; loss times analytically determined by scaling experimental results from a larger theta pinch; and loss time predicted by a zero dimensional computer code. It was determined that, for the 65 millitorr fill pressure, agreement between loss time predicted by these four techniques was good; however, both experimental uncertainties and loss time uncertainties were greater for the 50 millitorr fill pressure.IV

show abstract

The Helium-Neon laser

Allen

Jones

1965

Advances in Physics

View full text Add to dashboard Cite

Time-Dependent Electron Density Measurements in a Fast Theta-Pinch Discharge

Cited by 4 publications

References 4 publications

Laser action and plasma properties of an argon Z-pinch discharge

Laser action and plasma properties of an argon Z-pinch discharge

Studies of end loss from a theta pinch using a Twyman--Green interferometer. Scientific report 77-4

The Helium-Neon laser

Contact Info

Product

Resources

About