摘要:

Calibration of the Harvard College Observatory spectrometers that are to fly aboard the Apollo telescope mount (ATM) required a completely clean vacuum system having the capability for pumping hydrogen, helium, argon, and other inert gases at high speeds between10−6and10−8 Torr. The spectrometer performance would be degraded if contaminated by exposure to hydrocarbons, electromagnetic radiation, or metallic films. For this reason, a cryogenically pumped system was selected. This paper describes the concept, development, and operation of the vacuum system which was both cryo-condensation and cryosorption pumped in the molecular flow range. Molecular sieve, bonded to liquid helium-cooled panels, provided the clean, fast, and economical pumping device. Data presented show pumping speeds measured, adsorbent capacity of molecular sieve, liquid helium consumption rates, and cryogenic performance of the system. This data permits analysis of the cryo-vacuum pumping technique for other applications.

ISSN:0022-5355    

DOI:10.1116/1.1316325

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The deposition of 0.005 cm of lead-tin solder is required in the fabrication of flip-chip integrated circuits. Conventional bell jar techniques for coating masked wafers214-in.(5.7-cm) diam severely limited the batch size. Consequently, a 142-position, 5-tier “ferris wheel” dome, rotated at 5 rpm, was used. A low-voltage radiation heated source was mounted within the dome and was masked experimentally to attain uniform deposition rates on each tier. The vacuum system for this arrangement is fairly novel for the semiconductor industry. Instead of the conventional bell jar a box coater, about 36-in. (0.9-m) on a side, with a full opening front door is used. This provides for extremely flexible design and easy operation. Specifically the “shoe horn” tooling so characteristic of bell jars is avoided. The lead-tin evaporation source is extremely rugged and reliable even though it evaporates 3 lb at a time. Thickness is within the range of 0.0046–0.006 cm and maintenance is minimal.

ISSN:0022-5355    

DOI:10.1116/1.1316327

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

Ion nitriding hardening of steel surfaces has required a very special high-voltage cathode insulator supporting the work. The water-cooled chamber is grounded and is the anode of the system. A glow discharge at about 1000 V and pressures in the 1–15 Torr range in an atmosphere of mixed nitrogen and hydrogen heats the work to 1000 °F while bombarding its surface with nitrogen ions forming the hardening nitrides. A system with the cathode at ground potential has been built by inserting an intermediate chamber between the work-holding structure and the enclosing chamber. It was found easy to maintain the required pressures within the intermediate, reactive chamber while maintaining a vacuum high enough to eliminate glow discharge between the chambers. A description of the construction and operation of the equipment is given. It is proposed that this type of equipment could also be used for various thin-film components such as tantalum nitride resistors. Other gases could also be employed.

ISSN:0022-5355    

DOI:10.1116/1.1316328

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1316330

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

Measurements have been made of the evaporation characteristics of aluminum, alumina, aluminum nitride, barium titanate, boron carbide, boron nitride, carbon, copper, chromium, gold, iron, inconel, lead, magnesium, magnesium fluoride, molybdenum, nickel, niobium, permalloy, sapphire, silicon, silicon monoxide, silicon dioxide, silver, tantalum, tin, tin oxide, titanium, titanium monoxide, titanium dioxide, tungsten, and zinc. Using a 6-kW, 180 ° bent-beam gun, the deposition rate, required beam power, charge material form, and suitability for evaporation were determined for each material. The evaporation rate is reported in angstroms/minute. Methods of transferring these data to other guns are developed. The beam power limit is discussed and methods of increasing the evaporation rate of power limited materials are explored. Extension of these results to other materials is discussed and examples are given.

ISSN:0022-5355    

DOI:10.1116/1.1316331

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

This paper discusses the design of elastomer-sealed valves whose outgassing rate is greatly reduced and whose reliability of operation, particularly at elevated temperatures, is enhanced. Outgassing rates of new valve designs are presented and compared with those of conventional designs. It is seen that a 15X improvement can be made. The effect of this improvement on performance of typical small-vacuum systems is displayed graphically. A design is shown utilizing Viton as the main seal gasket which results in reliable and long life at 200 °C with the valve open or closed. Test data are presented. The problems encountered at elevated temperature by previous designs are examined and explained. The general character of elastomer seals is also examined at some length in an attempt to improve our understanding of it.

ISSN:0022-5355    

DOI:10.1116/1.1316332

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

A 1-in.-diam beryllium window of a thickness not to exceed 0.005 in. was developed.The window was electrically conductive to its mount and supported atmospheric pressure on one side while maintaining a low helium leak rate. An ultrahigh vacuum and pressure seal was built utilizing a beryllium to stainless-steel joint. A leak-tight configuration was maintained at 150-psi pressure and 200 °C. A beryllium 0.0005-in.-thick vacuum barrier 0.875-in. diam was developed to operate at 200 °C and to hold a differential pressure of10−3 Torr. The seal was accomplished by containing the beryllium foil in a nested gasket and clamping this “sandwich” in a modified commerical seal configuration.

ISSN:0022-5355    

DOI:10.1116/1.1316333

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

Pumpdown predictability of large pipe-type vacuum chambers is improved through design tradeoff reevaluation based on checkout anomaly analysis. Truncated-cone pipe chambers up to 2000 ft long and200 000 ft3in volume, which served as underground nuclear effects testbeds, were analyzed. Inconsistencies in evacuations to a base pressure of 1 mTorr are identified with the sorbing time variable of the chamber wall and experiment support materials. Variations in pressure levels along the pipe chambers are shown related to configuration factors and to design tradeoffs on allowable inleakage from concrete shrouding, sand stemming, and tunnel atmospheres. Cascading graphs innovated for tradeoffs include two recently derived flow conductance equations.

ISSN:0022-5355    

DOI:10.1116/1.1316334

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

Due to its unusual geometry and gas load, the SPEAR vacuum system incorporates several unique design features. The system consists of an aluminum chamber in the form of a 200-ft-diam ring which must achieve a pressure in the10−9 Torrrange with a large gas load due to synchrotron-radiation-induced desorption. Since the system is conductance limited, it was necessary to develop distributed sputter-ion pumps located within the chamber proper. A large number of aluminum-stainless-steel interfaces required the development and testing of various flange arrangements which would withstand a bakeout to 200 °C.

ISSN:0022-5355    

DOI:10.1116/1.1316335

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The seven main diffusion-pump vacuum systems on our Tandem Van de Graaff accelerator are controlled by a Honeywell H610 digital control computer. Each system has a local control panel with a hardwire protection shutdown system but no recovery capability. Control is normally left to the computer, which, through analog and digital inputs, senses trouble and secures the system according to the difficulty. The computer then recovers the systems completely or to the level of the difficulty. The computer operators’ console includes control buttons to enable/disable the securing function or the recovery function for a system. An alarm typewriter informs the operator of any action that the computer has taken, including which inputs are out of limit. An Adage AGT-10 display system shows each vacuum system and the status of each input. This takes the place of the usual remote indication panel.

ISSN:0022-5355    

DOI:10.1116/1.1316337

出版商:American Vacuum Society    

年代:1971

数据来源: AIP