Experiments with Supersonic Beams as a Source of Cold Atoms

Signal [V]
2.5
2.0
1.5
1.0
0.5
reference beam
19.2° 61 initial phase
11.3° 55 initial phase
6.2° 49 initial phase
0.16
0.08
0.00
0.0
4.5 5.0 5.5 6.0 6.5
Time of flight [ms]
6.0 6.2 6.4
Figure 4.18: A plot of the time of flight results of the metastable neon beam, varying
the phase in the 18 stage coilgun. Each curve is an average of 10 shots with a current
in the coils of 400 A, and the reference beam is the signal measured without pulsing
the coils. A greater phase angle leads to more slowing, but a smaller region of phase
stability, leading to fewer slowed atoms.
D-Sub connector feedthroughs from Accu-Glass.
4.4.5 18 Stage Data and Results
As noted above, during testing of the coils in vacuum, two of the coils (17
and 19) failed as the coil wire became shorted to the Permendur shell. Though the
coilgun was designed to use 20 coils, in the end only 18 are used for the slowing results
presented here. The data show the slowing of the beam from an initial velocity of
461 m/s. This is the target velocity chosen from a beam with a center velocity of
470 ± 1.8 m/s and a FWHM velocity of 43 m/s. From this target velocity, the path of
a synchronous atom is numerically integrated for a given phase, and the start time of
the pulse sequence is empirically scanned to optimize the slowed signal by matching
the target velocity simulated with the correct velocity group of the incoming beam.
The output velocity of the coilgun can be controlled by varying the phase used
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