Figure 1. Canal rays in a discharge tube from a sketch by Wien [2]. A = anode, K = cathode.
Figure 2. Willy Wien during his years at the Physikalisch-Technische Reichsanstalt in Berlin (1889-1896).
Figure 3. The house where Willy Wien was born on the farm called Gaffken west of Königsberg in East Prussia.
Figure 4.
Gas discharge tube with a mesh as the cathode behind which canal rays can be observed. The diagram is taken from an article written by Wien [6]. b = anode, a = cathode, C = electrode connected to an electrometer. The lower section of the tube up to the level of the cathode was placed in a grounded tin box.
Figure 5.
a: Two sets of tube apparatus for investigating canal rays with an electromagnet SN and an electric deflector plate in tube C (not marked). The fields are perpendicular to one another. The canal rays pass from tube b through a hole in the iron screen aa into tube C. A = anode, aa = cathode.
b: A similar setup to the one in Fig. 5a. K = cathode. The electric field between the plates aa is parallel to the magnetic field between the poles N and S. The back wall of the observation tube is within the magnetic field. The equations beside Fig. 8 apply to the deflection of the patch of light. Both diagrams are taken from articles written by Wien [6, 2].
Figure 6.
Gas discharge tube with a large bend in the tube between cathode K and anodes a and A; b = electrode connected to an electrometer; C = observation area for negative and positive, slow canal rays. The lower section of the tube up to the level of the anode was placed in a grounded tin box. The diagram is taken from an article written by Wien [6].
Figure 7.
Sketch of a parabola-image spectrograph constructed by Thomson for canal rays in 1897. K cathode, F capillary between discharge and observation tube, S observation screen, AA electric deflection plates, NS magnet, P iron shielding. At the left side of the apparatus, the pattern of the bright patch on S is sketched. Number 1 corresponds to the spot of atomic hydrogen, number 2 to that of molecular hydrogen. Both drawings are taken from the handbook of Radiology [2].
Figure 8.
The trajectory of canal rays in parallel electric and magnetic fields. The rays belong to ions of constant mass. The bended rays form a parabolic fluorescent strip at the observation screen. The formula of the deflections yeand ym by the electric and magnetic fields, respectively, have been taken from ref. [2]. V1 = potential at the electric deflection plates, l = distance of these plates, xe,m = distances the ions travel in the two fields, b = distance between the deflection plates and the observation screen,
Figure 9.
Part of the first time-of-flight spectrometer constructed by Hammer [14] for canal rays. The drawing has been taken from the handbook of Wien [2]. NS = magnet for deflection of the rays being produced in the discharge tube (not shown), B = first observation plane, Sp small aperture, A1,1, A1,2, A2,1, A2,2 = electric deflection plates, at the right second observation screen.
Figure 10.
Photographies of canal ray spots taken by Königsberger and Kilching [15] behind a parabola-image spectrograph. Left: discharge and observation tubes contain air (pE and pB are the corresponding pressures in mm Hg). Right: the filling is CO2.
Figure 11. Another example of canal ray spots taken by Retschinsky [16] with oxygen filling. a) the fill gas contains small amounts of mercury vapor. b) half of the fill gas is H2.
Figure 12.
Parabola-image spectrograph equipped with a glowing filament K for evaporation. The apparatus has been constructed by Dempster [19]. The ions are detected by means of a Faraday cup F behind a slit Sp. The poles of the magnet S and N are also the electric deflection plates. M is an iron shielding.
Figure 13. Current of the Faraday cup as a function of the magnetic field strenght. The curve was measured with the spectrograph shown in Fig. 12 at a pressure of 0.01 mm Hg. At this pressure, H3+ is the dominant ion of the mass spectrum.
Figure 14.
A mass spectrum of positive canal rays of methane measured with an parabola-image spectrograph. The photography has been made by Conrad (see Thomson's book [11]).
Figure 15.
Mass spectrograph of Aston [20]. The upper part of the figure shows the ion trajectories in the electric field between the deflection plates C and in the magnetic field M being perpendicular to the electric field. Ions of the same e/m value but different velocities meet at the focal point F. Theoretical calculations concerning the ion optics of this arrangement can be found in the handbook of Wien [2].
The realization of the spectrograph is sketched in the lower part of the figure. At the right: discharge tube with anode A, cathode K and a beam dump G for the cathode rays. The ions pass in front of the deflection plates and behind them fine slits Sb and D2 and penetrate then the magnet field M. Before making the photograph, the patch of the canal rays on the screen covered by Willemit W can be observed through the window F. L1 and L2 are pumps (liquid air traps).
Figure 16. Mass spectra of gases recorded by Aston's double focussing spectrograph. The gases are denoted at the right end of the photographic stripes. The various ions have been marked by their mass or the symbol of the element. Many of these ions are associated with - mostly organic - impurites of the fill gas.
Figure 17.
The optical line spectra of O2 and He measured by Stark [23]. Upper part: spark-spectrum of oxygen, lower part: spectrum of oxygen-canal rays, which move towards the observer. Wavelenght in Å.
Figure 18.
Apparatus constructed by Wien [23] to study light emission from canal rays by means of a high resolution prisma spectrograph. The electric oven was used as a source of black-body radiation.
Figure 19.
"Durchströmungsmethode" of Wien [26]. E = discharge area, K1, K2, K3 = capillaries, K = adsorbent cooled by liquid air, N-I and N-II = magnets.
Figure 20.
Apparatus constructed by Wien [2] for measuring the mean free path of canal rays for charge exchange in the gas of the observation tube (see text).
Figure 21.
Photographs of a canal ray behind the capillary separating discharge and observation tubes. left: medium vacuum pressure, right: low vacuum pressure ( < 10-4 mm Hg). See ref. [2].
Figure 22.
Splitting of the Hbline of hydrogen in an electric field of 104000 V/cm [29]. p = polarized parallel to the electric field, S = polarized perpendicular. The picture was taken from the handbook of Wien [2].
Figure 23.
Sketch of the aparatus used by Wien to detect the line splitting in the electyrodynamic field
Figure 24.
Electrodynamic splitting of the Hg line of hydrogen. In order to reduce the light emitted by atoms of the residual gas, the magnetic field strength was as high as possible (28000 Gauss) and the velocity of the canal rays correspondingly small (0.36 108 cm/s). A: light polarized perpendiculary to [
Figure 25.
Anode made from alkali halides and graphite. This anode was used in discharge tubes as source of secondary ions [33]. a = anode, K = cathode, G = patch of canal rays at the wall of the discharge tube.
