1. Pull Force Measurements of the Magnetized Beam Solenoid
Mentor: Riad Suleiman Tarek Eisa School: Woodside High School
Overview
Magnetized Beam Solenoid Magnet
Mapping Permanent Magnets
In order to keep the ions close to one another without drifting apart, Jefferson Lab’s Electron-Ion Collider will use an electron beam to cool the ions. This is accomplished when the electron beam is joined with the ion beam inside a long solenoid magnet, where the magnetic field makes the cooling of the ion beam more efficient. For this to work, the electron beam has to be generated inside another solenoid magnet (the electron beam is now called a magnetized beam). At the Gun Test Stand, a new solenoid magnet will be installed to generate and study magnetized beams [1]. The aim of this project is to measure the magnetic field of the solenoid magnet and to explore how a carbon steel puck enhances the solenoid’s magnetic field. The puck holds a photocathode material where an incident laser light generates electrons through photoemission. The puck is supported by a ceramic insulator, which is used to apply the high voltage to accelerate the electrons. Another goal is to measure the magnetic pull force of the solenoid magnet (how much force is exerted on the steel puck) in order to see if it’s powerful enough to damage the ceramic insulator.
The solenoid magnet is an electromagnet (it runs on electricity) made of copper. It uses a lot of power, so we have to run water through the coils in order to cool the solenoid magnet.
Size
ID=30 cm, OD=70 cm, W=16 cm
Conductor
L=500 m, 16 layers by 20 turns
Coil Weight
254 kg (560 pounds)
Resistance
0.18 Ohms
Voltage
73 Volts
Current
400 Amps
Power
29,200 Watts
To practice how to measure magnetic fields and forces, we started with permanent Neodymium magnets. A Hall Probe connected to a Gauss Meter was used to map the magnets. S N
Solenoid
Magnet
Ceramic
Insulator
Steel Puck
Magnetized
Electron
Beam
Gauss Meter
Hall Probe
Cathode
Our measured field map was consistent with the field values provided by the vendor on their website [2].
High Voltage
Vacuum
Chamber
Laser Beam
Mapping Solenoid Magnet
Measuring Pull Force on Steel Puck
Summary
The Hall Probe is used to map the new solenoid magnet at the Magnet Measurement Facility. The measured field agrees very will with the modeled field [3]. We also mapped the magnetic field with a steel puck positioned at 22 centimeters from the center of the magnet. The steel puck enhances the magnetic field at its face. The magnetic field of the solenoid magnet (without the steel puck) is 1,345 Gauss. With the steel puck, the field value near the face of the steel puck was enhanced to 2,470 Gauss.
To measure the magnetic force, we used an Electronic Portable Scale (normally used to weigh fish). We practiced measuring the pull force using permanent magnets and compared them to the pull force values provided by the vendor. We then measured the pull force between the puck and solenoid magnet. The steel puck was positioned 22 cm away because that’s how far it will be from the solenoid magnet when it’s installed in the high voltage vacuum chamber. The pull force came out to be 1.8 pounds.
The main goal of the project is to measure the pull force and the magnetic field of the magnetized beam solenoid magnet. We prepared for that by measuring permanent magnets with a Gauss Meter and a Hall Probe. We then mapped a solenoid magnet with and without a steel puck. We found that the steel puck enhances the magnetic field of the solenoid magnet. We measured the pull force on the steel puck in order to see if it is powerful enough to damage the ceramic insulator. We found that it was too weak to damage the ceramic insulator. In the near future, the solenoid magnet and the steel puck will be installed in the beamline at the Gun Test Stand to generate magnetized beam.
Acknowledgements
This is appreciation for everyone who’s helped me along the way and encouraged me to do better:
Riad Suleiman, Brita Hampton, Telesha Brown, Steve Gagnon,
Mike Beck, Joe Meyers, Joe Grames, Matt Poelker, Mamun Mamun,
Marcy Stutzman, and my Family and Friends.
Steel Puck
Photocathode
References
[1] "Generation and Characterization of Magnetized Bunched Electron Beam from DC Photogun for JLEIC Cooler." R. Suleiman and M. Poelker, Principal Investigators, Jefferson Lab Laboratory Directed Research and Development (LDRD) Project (2016).
[2] K&J Magnetics, Inc.,
[3] "Magnet Design for the Magnetized Beam LDRD Proposal.”  J. Benesch, Jefferson Lab Tech Note (2015).