摘要:
A superconducting high-field magnet coil system comprising several radially nested main coil sections (1, 2, 3, 4, 5) which are connected to each other in series in such a fashion that currents of the same direction flow through them during operation, wherein a first main coil section (EHS) is disposed radially further inward than a second main coil section (ZHS) and at least one intermediate main coil section (ZW) is disposed radially between the first and the second main coil section (EHS, ZHS), and with a superconducting switch (11) via which all main coil sections (1, 2, 3, 4, 5) can be superconductingly short-circuited in series, is characterized in that the first main coil section (EHS) and the second main coil section (ZHS) are directly successively series-connected and the first main coil section (EHS) and the second main coil section (ZHS) are bridged by a common quench protection element, which does not bridge the at least one intermediate main coil section (ZW). The magnet coil system realizes quench protection for selectively preventing excess currents in magnet coil areas in which the excessive mechanical force load associated with an excess current would damage the superconductor.
摘要:
A method for testing a new superconducting wire involves charging an actively shielded magnet coil configuration which comprises a first partial region which can be superconductingly short-circuited using an additional switch. A superconductor to be tested under increased current load is used in this first partial region, thereby preventing superconductor in the second partial region from being subjected to this increased current load. Operating currents are determined for both partial regions that have the desired excess current in the first partial region, with the overall field B0 only slightly differing from the standard operating field of the magnet coil configuration. The operating currents are adjusted through initial charging of the overall magnet coil configuration, thereby taking into consideration the inductive coupling between the partial regions and after closing of the additional switch, by continued charging or discharging in the second partial region only. The method permits inexpensive testing of a superconductor in a series-produced NMR magnet under NMR conditions.
摘要:
The invention concerns a method for charging a magnet arrangement (20) comprising a first partial region (21) which can be superconductingly short-circuited via an additional switch (23), and a second partial region (22), wherein the two partial regions (21, 22) generate, in an investigational volume (8), gradients of second order having different signs. A magnetic field dependence B* is measured close to the desired operating state of the magnet arrangement (20) and operating currents are determined for each of the two partial regions (21, 22) at which the overall magnetic field B in the volume (8) under investigation is freed from a magnetic field gradient of second order. These operating currents are set thereby taking into consideration the inductive coupling of the partial regions (21, 22) through initially charging of the overall magnet arrangement (20) and, after closing of the additional switch (23), through continuation of charging only in the second partial region (22). The magnetic field homogeneity of the magnet arrangement (20) can thereby be improved in a simple and inexpensive manner.
摘要:
A superconducting high-field magnet coil system comprising several radially nested main coil sections (1, 2, 3, 4, 5) which are connected to each other in series in such a fashion that currents of the same direction flow through them during operation, wherein a first main coil section (EHS) is disposed radially further inward than a second main coil section (ZHS) and at least one intermediate main coil section (ZW) is disposed radially between the first and the second main coil section (EHS, ZHS), and with a superconducting switch (11) via which all main coil sections (1, 2, 3, 4, 5) can be superconductingly short-circuited in series, is characterized in that the first main coil section (EHS) and the second main coil section (ZHS) are directly successively series-connected and the first main coil section (EHS) and the second main coil section (ZHS) are bridged by a common quench protection element, which does not bridge the at least one intermediate main coil section (ZW). The magnet coil system realizes quench protection for selectively preventing excess currents in magnet coil areas in which the excessive mechanical force load associated with an excess current would damage the superconductor.
摘要:
A method for testing a new superconducting wire involves charging an actively shielded magnet coil configuration which comprises a first partial region which can be superconductingly short-circuited using an additional switch. A superconductor to be tested under increased current load is used in this first partial region, thereby preventing superconductor in the second partial region from being subjected to this increased current load. Operating currents are determined for both partial regions that have the desired excess current in the first partial region, with the overall field B0 only slightly differing from the standard operating field of the magnet coil configuration. The operating currents are adjusted through initial charging of the overall magnet coil configuration, thereby taking into consideration the inductive coupling between the partial regions and after closing of the additional switch, by continued charging or discharging in the second partial region only. The method permits inexpensive testing of a superconductor in a series-produced NMR magnet under NMR conditions.
摘要:
A superconducting magnet coil system comprising a main field coil which is formed from series-connected sections, wherein the conductors of the radially inner sections contain a first superconducting material and have first electric voltage insulation, the conductors of the radially outer sections comprise a second superconducting material and are provided with second electric voltage insulation, wherein the first superconducting material has a higher critical magnetic field than the second superconducting material, and the first voltage insulation has a smaller dielectric strength than the second voltage insulation, and a shielding coil which is connected in series with the main field coil, radially surrounds the main field coil, and comprises conductors of the second superconducting material having the second electric voltage insulation, wherein the main field coil and the shielding coil are superconductingly short-circuited during operation and are protected through several ohmic resistances and/or diodes in case of a quench, is characterized in that the inner sections are protected by at least one ohmic resistance and the outer sections are protected, together with the shielding coil, by one single ohmic resistance.
摘要:
The invention concerns a method for charging an actively shielded magnet coil arrangement (20) comprising a first partial region (21) which can be superconductingly short-circuited using an additional switch (23), and a second partial region (22), wherein the two partial regions (21, 22) generate dipole moments of different signs. The magnetic fringe field B* is measured close to the desired operating state of the arrangement (20) and operating currents are determined for each of the two partial regions (21, 22) at which the overall magnetic field B is free from an additional dipole moment caused by production tolerances to permit setting of the theoretically optimum fringe field, irrespective of production tolerances. These operating currents are adjusted taking into consideration the inductive coupling between the partial regions (21, 22) through initially charging the entire magnet coil arrangement (20) and, after closing the additional switch (23), through continuation of the charging process in the second partial region (22) only. This eliminates deviations, which are caused by production tolerances, from the optimum theoretical fringe field of the arrangement (20) in a simple and inexpensive manner.
摘要:
An NMR magnet coil system, comprising superconducting conductor structures, with an inductance L0 for generating a homogeneous magnetic field B0 through which an operating current I0 flows in the persistent mode, and wherein further superconducting switches (S1, S2, . . . Sn−1) are each provided between two points (P1, Q1), (P2, Q2), . . . , (Pn−1, Qn−1) of the winding of the magnet coil system which, during operation, separately superconductingly short-circuit one or more disjoint partial regions (1, 2, . . . , n−1) with the inductances L1, L2, . . . , Ln−1 to generate magnetic field contributions B1, B2, . . . , Bn−1 to the homogeneous magnetic field B0, is characterized in that the following is valid: α = &LeftBracketingBar; L 0 ∑ j = 1 n ( L - 1 ) jn B j B 0 &RightBracketingBar; ≤ 0.8 wherein Bn is the magnetic field contribution to the homogeneous magnetic field B0 of the residual region (n) of the magnet coil system, reduced by the separately superconductingly short-circuited partial regions (1, 2, . . . , n−1) and having the inductance Ln, wherein (L−1)jn is the entry of the jth line and nth column of the inverse of the entire inductance matrix of the magnet coil system and wherein L0 is the total magnetic inductance (sum of all entries of the inductance matrix). This permits substantial compensation of magnetic field drift caused by a residual resistance in a winding of the superconducting conductor structures of the coil system with little technical effort and without using a separate drift compensation coil, even in existing coil systems.
摘要:
A superconducting magnet coil system comprising a main field coil which is formed from series-connected sections, wherein the conductors of the radially inner sections contain a first superconducting material and have first electric voltage insulation, the conductors of the radially outer sections comprise a second superconducting material and are provided with second electric voltage insulation, wherein the first superconducting material has a higher critical magnetic field than the second superconducting material, and the first voltage insulation has a smaller dielectric strength than the second voltage insulation, and a shielding coil which is connected in series with the main field coil, radially surrounds the main field coil, and comprises conductors of the second superconducting material having the second electric voltage insulation, wherein the main field coil and the shielding coil are superconductingly short-circuited during operation and are protected through several ohmic resistances and/or diodes in case of a quench, is characterized in that the inner sections are protected by at least one ohmic resistance and the outer sections are protected, together with the shielding coil, by one single ohmic resistance.
摘要:
The invention concerns a method for charging an actively shielded magnet coil arrangement (20) comprising a first partial region (21) which can be superconductingly short-circuited using an additional switch (23), and a second partial region (22), wherein the two partial regions (21, 22) generate dipole moments of different signs. The magnetic fringe field B* is measured close to the desired operating state of the arrangement (20) and operating currents are determined for each of the two partial regions (21, 22) at which the overall magnetic field B is free from an additional dipole moment caused by production tolerances to permit setting of the theoretically optimum fringe field, irrespective of production tolerances. These operating currents are adjusted taking into consideration the inductive coupling between the partial regions (21, 22) through initially charging the entire magnet coil arrangement (20) and, after closing the additional switch (23), through continuation of the charging process in the second partial region (22) only. This eliminates deviations, which are caused by production tolerances, from the optimum theoretical fringe field of the arrangement (20) in a simple and inexpensive manner.