A Fast Continuous Magnetic Field Measurement System Based on Digital Signal Processors

In order to study dynamic effects in accelerator magnets, such as the decay of the magnetic field during the dwell at injection and the rapid so-called "snapback" during the first few seconds of the resumption of the energy ramp, a fast continuous harmonics measurement system was required. A new magnetic field measurement system, based on the use of digital signal processors (DSP) and Analog to Digital (A/D) converters, was developed and prototyped at Fermilab. This system uses Pentek 6102 16 bit A/D converters and the Pentek 4288 DSP board with the SHARC ADSP-2106 family digital signal processor. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a rotating coil probe. Data acquisition is performed under a RTOS, whereas processing and visualization are performed under a host computer. Firmware code was developed for the DSP to perform fast continuous readout of the A/D FIFO memory and integration over specified intervals, synchronized to the probe's rotation in the magnetic field. C, C++ and Java code was written to control the data acquisition devices and to process a continuous stream of data. The paper summarizes the characteristics of the system and presents the results of initial tests and measurements

[1]  Gueorgui V. Velev et al..  Measurements of sextupole decay and snapback in Tevatron dipole magnets , 2004 .

[2]  J.M. Nogiec,et al.  A flexible and configurable system to test accelerator magnets , 2001, PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268).

[3]  D. E. Johnson,et al.  Compensation of time varying fields in the Tevatron superconducting magnets , 1989, Proceedings of the 1989 IEEE Particle Accelerator Conference, . 'Accelerator Science and Technology.

[4]  V. Shiltsev,et al.  Advances in the Understanding and Operations of Superconducting Colliders , 2005, Proceedings of the 2005 Particle Accelerator Conference.

[5]  D. A. Finley,et al.  Time Dependent Chromaticity Changes in the Tevatron , 1987 .

[6]  R. Carcagno,et al.  Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets , 2005, Proceedings of the 2005 Particle Accelerator Conference.

[7]  R. Carcagno,et al.  Field quality of the LHC inner triplet quadrupoles being fabricated at Fermilab , 2003, Proceedings of the 2003 Particle Accelerator Conference.

[8]  S. Sanfilippo,et al.  A SCALING LAW FOR PREDICTING SNAP-BACK IN SUPERCONDUCTING ACCELERATOR MAGNETS , 2004 .

[9]  S. Sanfilippo,et al.  A scaling law for the snapback in Superconducting accelerator magnets , 2005, IEEE Transactions on Applied Superconductivity.

[10]  J. M. Nogiec,et al.  EMS: A framework for data acquisition and analysis , 2002 .

[11]  R. H. Carcagno,et al.  MEASUREMENTS OF SEXTUPOLE DECAY AND SNAPBACK IN TEVATRON DIPOLE MAGNETS , 2004 .