The dipole, by virtue of its field index, provides both dispersion and focusing. The present operations envelope states that the supply for the electron dipole may not be operated at a current above 1800 A (4.4 GeV/c). The supply for the hadron dipole may not be operated above 1200 A (3.2 GeV/c).
The dipole for the HRS spectrometer is a superconducting, cryostable
magnet. Its basic parameters are an effective length of 6.6 
, a
bend radius of 8.4 , and a gap width of 25 
. It is configured to
achieve a 45 degree bending angle for 4 GeV/c momentum particles at a
central field excitation of 1.6 T. For the HRS dipole to reach 1.6 T
an operating current of about 1500 A is required.
The dipole has been designed to achieve cryostability up to a field of 2 T, and this property has been extensively tested up to a field of 1.6 T. The cryostable coils are equipped with an energy removal circuit to cover the possibility of an unrecoverable quench. However, this can only happen if the helium level drops below the coil during operation. The current to the coils will be provided by a Dynapower System power supply, which can operate up to 2000 A and 10 V. This power supply is located on the gantry beside the dipole, and will be cooled with a maximum water flow of 35 liters per minute. The flow of the magnet cooling water will be regulated by flow meters installed on the floor of Hall A. The total water flow needed to cool the 4 power supplies for the HRS magnet system (dipole and quadrupoles) amounts to 80 liters per minute, with a supply pressure of cooling water for Hall A of 100 psi.