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A distribution of charge or magnetization which produces an electric or magnetic field equivalent to that produced by two electric or magnetic dipoles whose dipole moments have the same magnitude but point in opposite directions, and which are separated from each other by a small distance.
A mass distribution that has unequal components of the moment-of-inertia tensor along the three principal directions.



a system of charged particles whose total electric charge and electric dipole moment equal zero.

Figure 1. Examples of relative location of dipoles in a quadrupole

A quadrupole can be considered a set of two identical dipoles with the dipole moments equal in magnitude but opposite in direction and separated by a certain distance. At great distances R from the quadrupole, the field intensity of the quadrupole E decreases in inverse proportion to R to the fourth power (E∼ 1/R4). The relationship between E and the charges and their location is described in the general case by a set of five independent values that together constitute the quadrupole moment of the system. The quadrupole moment also determines the energy of a quadrupole in an external electric field. In the case described by Figure 1 the absolute value of the quadrupole moment is equal to 2ela, where e is the charge, 1 is the dimension of the dipoles, and a is the distance between the centers of the dipoles. A quadrupole is a second-order multipole.


Landau, L. D., and E. M. Lifshits. Teoriia polia, 5th ed. Moscow, 1967, § 41.


References in periodicals archive ?
for lot 1 2 different magnets are procured: - quadrupole magnet q1, Length 48 cm, Number 2, - quadrupole magnet q2, Length 73 cm, Number 2.
The ion shield high efficiency source minimized fragmentation even at 70 eV, providing an optimum abundance and transmission of ions into the quadrupoles. Method settings were made to provide enough sensitivity to easily detect and quantify the target analytes at concentrations equal to or better than Method 608.
Unfortunately, inefficiencies in creating the ion packet, the production of distorted mass spectra, their physical size and relatively high cost make TOFs less appealing than quadrupoles for GC applications.
The established technique, quadrupole ICP-MS, provides routine trace analysis but is limited by spectral interference for certain analyses and complex matrices.
VG Quadrupoles has designs for the following configurations:
Analytical laboratories can now obtain high quality data with new triple quadrupole mass spectrometry technology designed to provide exceptional performance for the most demanding targeted quantitation applications in the environmental, food safety, pharmaceutical and biopharmaceutical industries as well as clinical research and forensic toxicology.
"Customers have said that they'd like to buy another one of our TSQ triple-stage quadrupole mass spectrometers, but they just don't have the room for it," says Warren.
In the event of the supplier~s bankruptcy without a legal successor who is ready to take over the production of the quadrupoles or their components, the client will receive a non-exclusive license to reproduce all the components of the quadrupole to ensure the operational readiness of Mesa.
Lot 2: production and delivery of 34 quadrupole magnets
The purpose of this alloti market, the production and delivery of 3 types of magnets on the French site of LAL in the ThomX project - Lot 1: production and delivery of 15 dipole magnets,- Lot 2: production and delivery of 34 quadrupole magnets,- Lot 3: production and delivery of 13 sextupole magnets.
1 Gas chromatography-triple quadrupole mass spectrometer system with autosampler, FID detector and thermal desorption
The interaction between the gradient magnet and the smaller quadrupole caused worry.

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