High Power Laser Science and Engineering, Volume. 6, Issue 2, 02000e17(2018)
A platform for high-repetition-rate laser experiments on the Large Plasma Device
Fig. 1. Schematic of the experimental setup in the LAPD. A high-repetition-rate laser hits a plastic target embedded in an ambient magnetized plasma. The target rotates and translates in between laser shots. The resulting interaction between the laser plasma and ambient plasma is scanned with magnetic flux (‘bdot’) probes and emissive Langmuir probes in two intersecting planes, –
(blue) and
–
(gray). The location of the high-density ambient plasma at
is shown in purple.
Fig. 2. Langmuir probe measurements of the initial electron density and temperature
in the
–
plane. The target is located at
.
Fig. 3. Composite plots of (a) the magnitude of the relative magnetic field and (b) the electrostatic potential
in the
–
and
–
planes at the same time
. Each plane is comprised of thousands of separate laser shots, showing a high degree of reproducibility. The target is located at
.
Fig. 4. Time series of surface plots of in the
–
plane, where the vertical dimension (color) is the magnitude of
. The target is at
and the background field
along
.
Fig. 5. Time series of contour plots of in the
–
plane. The target is at
.
Fig. 6. Measured and derived quantities in the –
plane at time
. (a) Measured vector magnetic field
. (b) Vector electric field
derived from the gradient of the measured electrostatic potential. (c)
-component of the current density
, derived from the measured magnetic field. (d) Charge density derived from the measured potential. (e) Profiles taken along
in (a)–(d). Also shown in (a)–(d) is an image of plasma self-emission at the same time.
Fig. 7. Measured and derived quantities in the –
plane at time
. (a)
-component of the measured relative magnetic field
. (b) Vector electric field
derived from the gradient of the measured electrostatic potential. (c) Vector current density
, derived from the measured magnetic field. (d) Charge density derived from the measured potential. (e) Profiles taken along
in (a)–(d). Also shown in (a)–(d) is an image of plasma self-emission at the same time.
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D. B. Schaeffer, L. R. Hofer, E. N. Knall, P. V. Heuer, C. G. Constantin, C. Niemann. A platform for high-repetition-rate laser experiments on the Large Plasma Device[J]. High Power Laser Science and Engineering, 2018, 6(2): 02000e17
Received: Dec. 1, 2017
Accepted: Feb. 6, 2018
Published Online: Jul. 4, 2018
The Author Email: D. B. Schaeffer (dschaeffer@physics.ucla.edu)