Magnet Options for Magnetic InterventionMagnet Options for Magnetic Intervention

SC Wire Characteristics (Critical Current Density: Jc)With the advent of cusp geometry for diverting ions into external dumps,

the necessity of high field magnets around the reactor chamber becomes a requirement. Given the current HAPL ‘tulip’ cusp configuration, magnets approximately 2.7 meters in diameter operating in the range of 10 to 20 Tesla are needed to provide these required fields. This study will review the state-of-the-art in high field magnet research, regarding design feasibility as well as reliability, in support of HAPL’s operational parameters.

Motivation

Magnetic Intervention Geometry “Evolution”Magnetic Intervention Geometry “Evolution”

4-coil Ring Cusp Octacusp(Multiple point cusps)

“Tulip” Design

Magnetic field guided ion trajectory of Tulip shape

A review of existing magnet technology, including conversations with staff at the Plasma Sciences and Fusion Center at MIT, has shown that while it is possible to build magnets capable of sustaining the basic operating parameters required by HAPL’s cusp configuration, it needs to be demonstrated that these magnets can perform reliably within HAPL’s proposed duty cycle. Today’s knowledge indicates that for the magnet size and fields required by HAPL, both the cyclic frequency and length of service for these magnets will be a challenging engineering endeavor. These conclusions encompass a study of superconducting, normal and hybrid magnet technologies. Further study, additional analysis and prototype development are strongly recommended actions that will further advance the feasibility of this concept. By working within realistic parameters, there is optimism that a designable magnetic intervention concept may be achieved.

ConclusionCurrent High Field Superconducting Magnets1. 21.1T 900MHz NMR magnet by NHMFL (National High Magnetic Field Lab): 105 mm bore.

2. 20T magnet by Oxford instruments: 52 mm bore.

3. 17.6T/750 MHz Spectrometer in McKnight Brain Institute, Univ. of Florida (manufacturer: Bruker): 89 cm bore.

4. 14T/600 MHz NMR Spectrometer in McKnight Brain Institute, Univ. of Florida: 51 mm bore.

5. Oxford 21.1T magnet (Varian INOVA 900): 63 mm warm bore.

6. Oxford 11.7T magnet (Varian 500 wide Bore): 89 mm warm bore.

7. 11.7T/500 MHz (Bruker Avance 500 Wide Bore): 89 mm warm bore.

To build a 20T magnet with min coil pack diameter of 2.7m and coil pack current of 27.5E6 A-turns is still challenging. A possible solution may be using HTS (e.g. BSCCO) at LHe temperature.

Also some future work can be done to seek for an optimal magnet design to minimize coil pack current but producing same ion trajectory.

Overview of SC capability by Oxford Instruments

8-coil magnetic intervention design with max B=~20T and coil

pack i=27.5E6 A-turns

For reference1,2, the 45 Tesla hybrid magnet at the National High Field Magnet Lab (NHMFL) in Florida is only a few inches in size and consumes up to 33MW during operation. If scaled up to the dimensions required for the HAPL cusp design, not only would the power consumption be significant, but the high forces and stresses associated with such a magnet would require a major support structure.Note that the NHMFL outsert is being operated at 11T and the resistive magnet at 34T, with a power consumption of the resistive insert much larger than 20MW1.1The Projected 45T Hybrid Magnet System at the Nijmegen High Field Magnet Laboratory; J. Perenboom, S. Wiegers, et. al., IEEE Transactions on Applied Superconductivity, Vol. 18, No. 2, June 2008.2http://www.magnet.fsu.edu/mediacenter/features/meetthemagnets/hybrid.html

National High Magnetic Field LabNational High Magnetic Field Lab45 Tesla Hybrid Magnet45 Tesla Hybrid Magnet

I. Zatz, H. Zhang, C. Priniski, T. Dodson, C. GentilePrinceton Plasma Physics Laboratory

ANSYS Analysis of 8 Coil Configuration

19th High Average Power Laser Program Workshop, October 22nd-23rd, 2008, University of Wisconsin, Madison, WI