1. A sensor element for determining a concentration of at least one gas component in a gas mixture, comprising:
at least one first electrode exposed to the at least one gas component to be analyzed;
a second arrangement;
at least one reference electrode electrically interconnected by a first solid electrolyte to the at least one first electrode, wherein the second arrangement is configured to measure an electric current at least one of continuously and non-continuously between the at least one first electrode and one of the at least one reference electrode and a counterelectrode, in response to at least one of the applying and the setting an electric voltage between the at least one first electrode and the at least one reference electrode due to a chemical reaction proceeding at the at least one first electrode, the concentration of the at least one gas component in the gas mixture being determinable from the electric current; and
a first arrangement configured to at least one of apply and set the electric voltage between the at least one first electrode and the at least one reference electrode only during recurring time intervals;
wherein the second arrangement is configured to measure the electric current between the at least one first electrode and one of the at least one reference electrode and the counterelectrode, at least intermittently within the recurring time intervals.
2. The sensor element of claim 1, further comprising:
at least one reference gas channel, wherein the at least one reference gas is applied to the at least one reference electrode via the at least one reference gas channel.
3. The sensor element of claim 1, wherein the sensor element includes a first chamber, to which the gas mixture can be applied, that is provided with a second electrode which is connected to the counterelectrode via a second solid electrolyte, and a second chamber, downstream of the first chamber and connected to the first chamber in a gas-permeable manner, in which the at least one first electrode is positioned.
4. The sensor element of claim 3, wherein the first chamber together with the second electrode and the counterelectrode is a pump cell for electrochemically pumping off oxygen from the gas mixture.
5. The sensor element of claim 3, further comprising:
a first diffusion barrier positioned in the first chamber; and
a second diffusion barrier positioned in the second chamber;
wherein the gas mixture at least one of accesses the first chamber via the first diffusion barrier and accesses the second chamber via the second gas diffusion barrier.
6. The sensor element of claim 1, wherein the first arrangement includes an electric circuit and a voltage source for generating at least one of a specific electric voltage and a predefinable electric voltage that is constant during the recurring time intervals.
7. The sensor element of claim 1, wherein the first arrangement is configured to select a length of the recurring time intervals so that the electric current, which is measured as a function of time during the recurring time intervals, between the at least one first electrode and the at least one reference electrode is greater than a limiting current, measured at a constant electric voltage during a corresponding time.
8. The sensor element of claim 1, wherein, outside the recurring time intervals:
the electric voltage at least one of applied and set by the first arrangement is at least one of smaller than within the recurring time intervals and is at least nearly zero;
the first arrangement is electrically separated from at least one of the at least one first electrode and the at least one reference electrode outside of the recurring time intervals.
9. The sensor element of claim 1, wherein the second arrangement includes at least one of:
a current measuring device for one of point-by-point recording and continuous recording of the electric current during the recurring time intervals; and
an integrator circuit for recording an integral of the electric current, the integrator circuit forming the integral during a measuring interval at least one of lying within a recurring time interval and coinciding with the recurring time interval.
10. The sensor element of claim 1, wherein one of the following is satisfied:
the at least one first electrode is at least one of supplied with a storage arrangement to store temporarily the at least one gas component to be analyzed; and
the storage arrangement to store temporarily the at least one gas component to be analyzed is provided in a vicinity of the at least one first electrode.
11. The sensor element of claim 10, wherein the storage arrangement includes one of a layer applied on the at least one first electrode, and a material integrated into the at least one first electrode, the layer and material including at least one of barium oxide, barium carbonate and cerium oxide.
12. The sensor element of claim 10, wherein the storage arrangement enriches the at least one gas component to be analyzed outside of the recurring time intervals.
13. A method for determining a concentration of at least one gas component in a gas mixture using a sensor element that includes at least one first electrode exposed to the at least one gas component to be analyzed, at least one reference electrode electrically interconnected by a first solid electrolyte to the at least one first electrode, comprising:
at least one of applying and setting an electric voltage between the at least one first electrode and the at least one reference electrode only during recurring time intervals due to a chemical reaction proceeding at the at least one first electrode; and
measuring an electric current at least one of continuously and non-continuously, between the at least one first electrode and the one of at least one reference electrode and a counterelectrode, in response to the at least one of applying and setting an electric voltage between the at least one first electrode and the at least one reference electrode due to a chemical reaction proceeding at the at least one first electrode, the concentration of the at least one gas component in the gas mixture being determinable from the electric current;
wherein the measuring of the electric current between the at least one first electrode and the counterelectrode is performed at least intermittently within the recurring time intervals.
14. The method of claim 13, wherein the recurring time intervals recur periodically and have a length of 1 ms to 100 ms, and pause intervals of 1 ms to 100 ms lie between the recurring time intervals.
15. The method of claim 13, wherein at the at least one first electrode, the at least one gas component includes nitrogen oxide to be analyzed, and reacts to form oxygen and nitrogen, the oxygen thus formed being removable through the first solid electrolyte via the electric voltage at least one of applied and set during the recurring time intervals.
16. The method of claim 13, wherein a length of the recurring time intervals is selected so that the electric current between the at least one first electrode and the at least one reference electrode, measurable during the recurring time intervals as a function of time, is greater than a limiting current measurable at a constant electric voltage at a corresponding time.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
I claim:
1. A magnetic resonance apparatus having a single-circuit cooling circulation system operated with a coolant for cooling a gradient coil system so that the temperature of at least one surface of the gradient coil system remains within a prescribable temperature range, said cooling circulation system having a dimensioning performance corresponding to an average ohmic dissipated power of the gradient system, the cooling circulation system containing a heat exchanger that can at least be switched on and off, the heat exchanger having a high-frequency onoff switching clock, the gradient coil system having a high average specific heat capacity and the coolant having an operating temperature range proceeding beyond the prescribable temperature range.
2. A magnetic resonance apparatus according to claim 1, wherein the period of the onoff switching clock is less than ten minutes.
3. A magnetic resonance apparatus according to claim 1, wherein the average specific heat capacity is greater than approximately 1 JgK.
4. A magnetic resonance apparatus according to claim 1, wherein the gradient coil system comprises a casing of casting resin.
5. A magnetic resonance apparatus according to claim 1, wherein the heat exchanger is an air-cooled heat exchanger of an interior construction.
6. A magnetic resonance apparatus according to claim 1, wherein the heat exchanger contains a ventilator that is fashioned at least to be switched on and off.
7. A magnetic resonance apparatus according to claim 1, wherein the heat exchanger contains a refrigeration system that contains a refrigeration compressor that is constructed at least to be switched on and off.
8. A magnetic resonance apparatus according to claim 1, wherein the coolant is a cooling fluid.
9. A magnetic resonance apparatus according to claim 8, wherein the cooling fluid is water.
10. A magnetic resonance apparatus according to claim 1, wherein the cooling circulation system contains a temperature sensor for determining a run-up temperature, the cooling circulation system includes a two-point regulator for regulating variables in the run-up temperature and for manipulating variables and which operates the onoff switching of the heat exchanger and the two-point regulator comprises a small switching difference for achieving a high-frequency onoff switching clock.
11. A magnetic resonance apparatus according to claim 1, wherein the magnetic resonance apparatus comprises a permanent magnet as a basic field magnet and the gradient coil system is arranged at the permanent magnet.