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Backward-wave tubes (BWT) developed in Russia do not have
any foreign analogues. BWTs are monochrome microwave oscillators
of extremely high frequency. They possess unique possibility
of tuning the operating frequency in a wide range (up to ±30
% of the nominal value).
The BWTs can operate in their designed regime only when put
into a uniform magnetic field. Electromagnets were formerly
used to provide this magnetic field. However, the use of cumbersome
electromagnet with power source reduced the independence and
significantly increased the cost of the devices. This limits
the range of possible applications of BWTs.
Photo 1. Magnetic
system "Orchid"
The permanent magnetic system "Orchid" (see Photo 1
and Fig. 1) (technical specification ÌÀÅÐ.684116.136)
to replace the electromagnet for BWT has been developed and
put into mass production by the R&PC "Magnets and
Magnetic Technologies". This magnetic system ensures
stable operation of BWTs in a wide frequency range up to 150
GHz.
Figure 1. Design of
the "Orchid" magnetic system
This magnetic system creates a high-uniformity magnetic field
with strength greater than 1.2 T within a cylindrical volume
with diameter 45 mm and length 33.5 mm. Maximum field strength
deviation in the area of slow-wave structure of BWT is 2 %.
The parameters of real magnetic systems are shown in Figure
2.
Figure 2. Magnetic induction
in the operating volume of the "Orchid" magnetic
system. Distribution of the longitudinal component along the
longitudinal and transversal directions (Bz(Z)
and Bz(R), respectively) is plotted.
A series of systems for BWT was developed on
the basis of the "Orchid" magnetic system. |
