Apparatus for a nuclear resonance imaging (MRI) machine (100) that includes plasma elements (104, 106, 108). The MRI machine (100) includes gradient coils (104) that generate time-dependent gradient magnetic fields, transmitting elements (106) that excite target molecules (120) with RF energy (122), and receiving elements (108) responsive to RF energy (124) emitted by the excited molecules (120). The gradient coils (104) include plasma conductors (710) in which the plasma (716) is ignited by an exciter (208). The plasma conductors (710) are electrically connected to a gradient amplifier (206) that outputs a signal to produce the gradient fields. The transmitting elements (106) are plasma devices (710) configured to emit RF energy (122). The receiving elements (108) are plasma devices (710) responsive to emitted RF energy (124). An RF exciter (218) selectively and alternatingly ignites said plasma devices (710) to avoid coupling and interference between them.

An exemplary coil arrangement can be provided, which can include, for example, coil element(s) having a parallel resonant circuit at a port, where the coil element(s) is detuned by causing a low impedance at the port. Pre-amplifier arrangements can provide a low impedance at the port of the coil element(s) to suppress the induced current on the coil element(s) thereby reducing the inductive coupling to neighboring element(s). The coil element(s) can include an inductance and a capacitance which cancel each other out. The inductance and the capacitance can cancel each other out such that an impedance of the coil element has no imaginary part at a working frequency. An impedance of the coil element(s) in free space includes a real part that can be greater than a sum of losses for the coil element(s).

An apparatus includes an RF power amplifier with a controller and an impedance matching network. The RF power amplifier is configured to drive a load in electrical communication with the RF power amplifier. The impedance matching network is located electrically between the RF power amplifier and the load. The impedance matching network is configured to match an output impedance of the RF power amplifier and an impedance of the load. The impedance matching network includes a set of fixed value impedance matching circuits configured to provide different discrete values. The RF amplifier includes a variable DC power supply powering RF transistors to result in a variable output impedance for the amplifier. The controller selects an impedance matching circuit of the capacitor presets and/or the right setting for the variable DC supply that result in minimum reflected power to match the output impedance of the amplifier to the output load impedance.

In one example, an RF coil array includes a first RF coil configured to generate a magnetic field along a first axis, the first RF coil having a first surface, a second RF coil configured to generate a magnetic field along a second axis, orthogonal to the first axis, the second RF coil having a second surface, and a first foldable interconnect coupling the first RF coil to the second RF coil. The first foldable interconnect may be adjusted to couple the first RF coil to the second RF coil with a first amount of overlap and with the first surface and second surface facing a common direction, or couple the first RF coil to the second RF coil with a second amount of overlap, larger than the first amount of overlap, and with the first surface in face to face position with the second surface.

An NMR well logging tool is provided that includes a sensor and associated electronic circuitry. The sensor includes an array of RF antenna elements. The electronic circuitry includes at least one low-power integrated circuit and a plurality of high-power modules corresponding the RF antenna elements of the array. Each high-power module is coupled to a corresponding RF antenna element of the array and includes an RF amplifier that is configured to amplify RF pulses generated by the at least one low-power integrated circuit and supplied thereto for transmission by the corresponding antenna element. In embodiments, the RF amplifier of each high-power module can include an H-bridge circuit or other suitable RF amplifier.

An anti-saturation device for a ground magnetic resonance signal amplifying circuit has a receiving coil connected with a band-pass filter circuit through a pre-amplifying circuit and a programmable amplifying circuit. The programmable amplifying circuit is connected with an AD acquisition card through the band-pass filter circuit. The band-pass filtering circuit is connected with a computer through the AD acquisition card, and the AD acquisition card is connected with an emitting system through the computer. An automatic amplification factor adjusting module is embedded into a nuclear magnetic resonance detector, and can also directly replace a receiving amplification circuit of the nuclear magnetic resonance detector to work independently.

An imaging system comprises determination of a charge block for each building block of an MRI pulse sequence and for each readout event of the MRI pulse sequence, determination, for each charge block, of a charge per request associated with the charge block, determination, for each charge block, of an associated charge reduction based on a charge per request associated with the charge block and on a charge available to the charge block after execution of a previous charge block of the MRI pulse sequence, determination, for each charge block associated with a non-zero charge reduction, of a flip angle of a corresponding building block of the MRI pulse sequence based on a charge per request and a charge reduction associated with the charge block, and control of a radio frequency system to deliver the MRI pulse sequence based on the determined flip angles of each building block of the MRI pulse sequence corresponding to a charge block associated with a non-zero charge reduction.

A coil assembly includes: a radio frequency (RF) coil operable to be placed over a portion of a subject; a quarter-wave transformer coupled to the RF coil and configured to transform a characteristic impedance of the RF coil; and a diode placed behind the quarter-wave transformer and away from the RF coil, wherein the diode is operable to: (i) when the diode is forward biased, the diode turns the quarter-wave transformer into an open circuit such that the power amplifier drives the RF coil with sufficient electrical power for the RF coil to transmit an RF pulse into the portion of the subject; and (ii) when the diode is provided zero or revers bias, the diode turns the quarter-wave transformer into a short circuit such that the RF coil is detuned from a Lamor frequency of nuclei of interest immersed in the main magnet.

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B.sub.0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B.sub.0 field.

A power supply facility for supplying a magnetic resonance facility with electrical power includes a control facility, a network connection to a power network, and an electrical energy store, such as a battery. The network connection is configured for an installed power level that is lower than a maximum power level that may be demanded by the magnetic resonance facility. The control facility is configured, in the event that a power demand of the magnetic resonance facility exceeds the installed power, to provide the power from the network connection and the energy store.