| 摘要 |
956,142. Determining physical qualities of materials. VARIAN ASSOCIATES. May 31, 1960 [June 1, 1959], No. 41217/62. Divided out of 956, 141. Heading G1N. A circuit supplying current to an ion vacuum pump or gauge 5<SP>1</SP> comprises a voltage doubling circuit 4 having a series capacitor of low value 16 to limit short circuit currents. The vacuum pressure is a function of the output current which is measured by an indicating instrument 43 shunted by a rectifier 42 which has no effect at low currents but provides an increasing shunting effect at higher currents so that the upper end of the instrument scale may be compressed. Another rectifier 47 by-passes reverse voltages. To indicate small current changes a range switch 49 is closed reducing the circuit resistance, the zero being arbitrarily adjusted by resistors 46, 51. A recording instrument may be tapped across a series resistor 44. The current may be adapted to A.C. by the substitution of an A.C. instrument. |
