64
3.
OF THE ELECTRON
A hot lament may be used to produce electrons instead of the
cold discharge. A spiral of nickel strip, with one edge toward the
anode, is coated with barium and strontium oxides and mounted
with its center on the axis about 10 centimeters from the anode.
Due to the heat from the lament, cooling of the waxed joint at D
must be provided and any ground joint, for filament replacements,
should be well back from the lament.
Also, with a filament, the
gas
leak shown in the gure is not needed.
A branch pumping line
near the lament is used to keep the pressure
in the source chamber
as low as possible.
The central section, Â, consists of an iron rod about 15 centimeters long and about 7 centimeters in diameter through which
various holes are drilled as shown.
The axial hole, between H and
H, is 2—3 centimeters in diameter and about 10 centimeters long.
It is closed by brass discs pierced with 1 millimeter holes and
covered with thin copper.
Small holes, HH, 0.2 to 0.3 millimeters
in diameter, are drilled in this thin copper.
Great care must be
taken that both of these holes are on the axis of the tube.
As an
alternative for ease of replacement and adjustment, the discs and
thin copper may be mounted in the ends of a brass tube which is
slipped into the axial hole in the iron. Air from a drying tube is
admitted to the discharge tube through the lavite cone leak.
Mercury is raised or lowered around this cone to vary the rate at
Which air is admitted.
Rapid pumping is used to keep the right
side of the apparatus at as low a pressure as possible.
The pump—
ing tube shold be as large as possible, say 2 to 4 centimeters.
The crystal or foil material is mounted with clips over a hole
in the end of the rod R.
A sylphon bellows 2 to 3 centimeters in
diameter is used as a exible seal.
The crystal position is altered
by three screws SSS (only two are shown) and is observed through
a side window.
New crystals are inserted from the observation
end P by removal of the metal tube T.
For transmission experi—
ments, of the type of G. P. Thomson, the foil thickness should be
10“5 to 10“6 centimeter.
The foils may be prepared by mounting
commercial gold foil on a platinum grid and reducing the thickness of the gold with acid.
Another process is to sputter or evap—
orate a thin layer of gold on glass, coat with lacquer, dry, strip ofÏ
the lacquer and gold from the glass, place over a platinum grid in
3.
OF THE ELECTRON
A hot lament may be used to produce electrons instead of the
cold discharge. A spiral of nickel strip, with one edge toward the
anode, is coated with barium and strontium oxides and mounted
with its center on the axis about 10 centimeters from the anode.
Due to the heat from the lament, cooling of the waxed joint at D
must be provided and any ground joint, for filament replacements,
should be well back from the lament.
Also, with a filament, the
gas
leak shown in the gure is not needed.
A branch pumping line
near the lament is used to keep the pressure
in the source chamber
as low as possible.
The central section, Â, consists of an iron rod about 15 centimeters long and about 7 centimeters in diameter through which
various holes are drilled as shown.
The axial hole, between H and
H, is 2—3 centimeters in diameter and about 10 centimeters long.
It is closed by brass discs pierced with 1 millimeter holes and
covered with thin copper.
Small holes, HH, 0.2 to 0.3 millimeters
in diameter, are drilled in this thin copper.
Great care must be
taken that both of these holes are on the axis of the tube.
As an
alternative for ease of replacement and adjustment, the discs and
thin copper may be mounted in the ends of a brass tube which is
slipped into the axial hole in the iron. Air from a drying tube is
admitted to the discharge tube through the lavite cone leak.
Mercury is raised or lowered around this cone to vary the rate at
Which air is admitted.
Rapid pumping is used to keep the right
side of the apparatus at as low a pressure as possible.
The pump—
ing tube shold be as large as possible, say 2 to 4 centimeters.
The crystal or foil material is mounted with clips over a hole
in the end of the rod R.
A sylphon bellows 2 to 3 centimeters in
diameter is used as a exible seal.
The crystal position is altered
by three screws SSS (only two are shown) and is observed through
a side window.
New crystals are inserted from the observation
end P by removal of the metal tube T.
For transmission experi—
ments, of the type of G. P. Thomson, the foil thickness should be
10“5 to 10“6 centimeter.
The foils may be prepared by mounting
commercial gold foil on a platinum grid and reducing the thickness of the gold with acid.
Another process is to sputter or evap—
orate a thin layer of gold on glass, coat with lacquer, dry, strip ofÏ
the lacquer and gold from the glass, place over a platinum grid in