Magnetic Injection Scheme for The Atom Laser Karl

Magnetic Injection Scheme for The Atom Laser Karl Lundquist REU Summer 2010 Raithel Lab August 17 2010

Outline • Overview of current generation atom laser setup • Theory/Simulation of magnetic injection • Experimental setup of magnetic injection o In the vacuum o Electronics o Enclosure o Software

Overview of current setup • • Zeeman slower Primary MOT Pusher Beam Secondary MOT Magnetic Injection Magnetic Compression Surface Adsorption evaporative cooling • Continuous BEC!

Basic idea behind magnetic injection • Transferring atom into evaporative cooling region with light would cause atoms to gain heat. • Instead, if we transfer atoms with magnetic field only, the process can be slow enough to be adiabatic. • From secondary MOT, we can transfer atoms along the guide using a moving magnetic field minimum.

Magnetic field sources in the injection region • Guiding wires produce transverse trapping potential (~250 amps) • Injection coils produce moving magnetic field minimum (2 -3 amps each) • Racetrack coils produce quadrupole magnetic field for secondary MOT

Coil current profiles Period ~ 1 second

Injection Simulation

High Current Power Supply • • HP 6651 A 0 -8 Volts 0 -50 Amps Low gauge wire and aluminum rods for high current transport

Circuit setup • Need easy way to control current in each coil with low voltage signal from computer • Traditional differential amplifier setup • Must drop signal over R test in order to maintain equilibrium • op-amp pushes transistor base until allowed current causes required voltage drop • R=. 5 Ohms • I=V/R => I = 2 V*(1/Ohm) • Directly proportional

Testing • Measuring voltage across load resistor will indicate the amount of current flowing through coils • A circuit can be tested by checking that the signal in is identical to the signal out

Cooling • 2 -3 Amps through transistors makes them very hot • use heat sinks and high powered fans too keep them cool

Circuit Control • United Electronics Industries Power. DNA Cube • Allows for DAQ communication via Ethernet port • Lab. VIEW user interface

Acknowledgments Much thanks to everyone in Raithel Lab for a great summer! • • • Georg Raithel Andrew Schwarzkopf Andrew Cadotte David Anderson Eric Paradis Mallory Traxler • • • Sarah Anderson Erik Power Betty Slama Stefan Zigo Kareem Hegazy Kevin Smith