BEC preparation

There are 28 steps in electronics while the ultracold atomic cloud is prepared.

1. MOT preparation

Magnetic coils

Inductance 40 mH, How the switch on time is different from switch off, why it moves during one process?

January 2020

Measurement with a network analyzer and the test coil:

Resonant freq. [kHz]	Capacitance [nF]	Li [mH]	Conditions
1510	0		Only the coil
718.25	0.47	3.9
520	1	3.25	102
371	2.2	3.1
173.75	10	3.27	103

Measurement with a network analyzer and experimental coils connected in series, measured near MOSFETs:

Resonant freq. [kHz]	Capacitance [nF]	Li [mH]	Conditions
391	0		Only the coil
317	0.47	7.2

$\omega_0 =1/\sqrt{L C_0}$

$L C_0 =1/\omega_0^2$

$L_i = (1/\omega_i^2-1/\omega_0^2)/C_i$

Switching times

There are 24 MOSFETs (BZW50-47L) connected in parallel, we connect a TSV diode for each raw (IXN 180N25T). 420 A and 7 mH results in 617 J of energy stored. The peak voltage 2.9 kV is generated if we make the switching 1ms. In Spielman's group they claim to achieve a few us switching time (p 74. Garcia's thesis). Another option is to follow the technique proposed in Toronto.