Development program on a Spindt cold-cathode electron gun

A thin film field emission cathode (TFFEC) array and a cold cathode electron gun based on the emitter were developed. A microwave tube gun that uses the thin film field emission cathode as an electron source is produced. State-of-the-art cathodes were fabricated and tested. The tip-packing density of the arrays were increased thereby increasing the cathode's current density capability. The TFFEC is based on the well known field emission effect and was conceived to exploit the advantages of that phenomenon while minimizing the difficulties associated with conventional field emission structures, e.g. limited life and high voltage requirements. Field emission follows the Fowler-Nordheim equation

Evaluation of volcano-style field ionization source and field emitting cathodes for mass spectrometry and applications

A volcano-style field ionization source was tested with eight different gases: hydrogen, helium, ammonia, methane, argon, neon, water vapor, and hydrogen sulfide. For ammonia, hydrogen sulfide, and water, the ionization efficiency of the field ionization source was determined as a function of the electrical potential difference between the ionizer and its counterelectrode. The ionization efficiencies for the other gases were too low to be measured in the present apparatus. The operating characteristics of a field emission cathode, were studied, in the presence of the same eight gases at pressures up to 0.00001 torr. The presence of the gases caused little or no significant change in the electron emission from the cathodes. Results indicate that the field emission cathode has advantages over electrically heated cathodes as a source of an electron beam in spacecraft mass spectrometers

Offer Price, Target Ownership Structure and IPO Performance

Although the choice of an IPO offer price level would seem to have little economic significance, firms do not decide this arbitrarily. Our findings suggest that firms select their IPO offer prices to target a desired ownership structure, which in turn has implications for underpricing and post-IPO performance. Higher priced IPOs are marketed by more reputed underwriters and attract a relatively larger institutional investment. These IPOs are relatively more underpriced, possibly as compensation for the monitoring and information benefits provided by institutional investors. IPOs whose offer prices are below the median level seem to be targeted towards a retail investor clientele. These IPOs are also relatively more underpriced, possibly as a cost of adverse selection. Our finding that long-run performance increases with offer price confirms that higher priced IPOs are better firms.Initial public offerings; share prices; share allocation

Is Share Price Related to Marketability? Evidence from Mutual Fund Share Splits

We examine the "marketability hypothesis," which states that stock splits enhance the attractiveness of shares to investors by restoring prices to a preferred trading range. We examine splits of mutual fund shares because they provide a clean testing ground for the marketability hypothesis, since the conventional rationales for common stock splits do not apply. We find that splitting funds experience significant increases (relative to non-splitting matched funds) in net assets and shareholders. Stock splits do appear to enhance marketability.

Credit Enhancement through Financial Engineering: Freeport-McMoRan's Gold-Denominated Depository Shares

In 1993 and early 1994, Freeport McMoRan Copper and Gold (FCX), a mining company, issued two series of gold-denominated depositary shares to raise 430 million dollars expanding their mining capacity in Indonesia. We price the depositary shares using a term structure model for the forward rates implied by gold futures and we show that FCX successfully enhanced the credit quality of the issue. This credit enhancement is achieved because the effect of linking the payoff of the depositary shares to gold reduces default risk and is similar to conventional risk management. However, the bundling of financing and risk management allows the firm to target hedging benefits only to the newly issued securities. The design of the security also overcomes the asset substitution problem. The depositary shares issued by FCX illustrate how firms can enhance credit quality through financial engineering without changing the existing priority ordering of their capital structure.Risk management, Gold-linked, Hybrid Securities

Spindt cold cathode electron gun development program

A thin film field emission cathode array and an electron gun based on this emitter array are summarized. Fabricating state of the art cathodes for testing at NASA and NRL, advancing the fabrication technology, developing wedge shaped emitters, and performing emission tests are covered. An anistropic dry etching process (reactive ion beam etching) developed that leads to increasing the packing density of the emitter tips to about 5 x 10 to the 6th power/square cm. Tests with small arrays of emitter tips having about 10 tips has demonstrated current densities of over 100 A/sq cm. Several times using cathodes having a packing density of 1.25 x 10 to the 6th power tips/sq cm. Indications are that the higher packing density achievable with the dry etch process may extend this capability to the 500 A/sq cm range and beyond. The wedge emitter geometry was developed and shown to produce emission. This geometry can (in principle) extend the current density capability of the cathodes beyond the 500 A/sq cm level. An emission microscope was built and tested for use with the cathodes

Development program on a cold cathode electron gun

A prototype electron gun with a field emitter cathode capable of producing 95 mA in a 1/4 mm diameter beam at 12 kV was produced. Achievement of this goal required supporting studies in cathode fabrication, cathode performance, gun design, cathode mounting and gun fabrication. A series of empirical investigations advanced fabrication technology: More stable emitters were produced and multiple cone failure caused by chain reaction discharges were reduced. The cathode is capable of producing well over 95 mA, but a substantial collector development effort was required to demonstrate emission levels in the 100 mA region. Space charge problems made these levels difficult to achieve. Recommendations are made for future process and materials investigation. Electron gun designs were modeled and tested. A pair of two-electrode gun structures were fabricated and tested; one gun was delivered to NASA. Cathodes were pretested up to 100 mA at SRI and delivered to NASA for test in the gun structure

Credit Enhancement Through Targeted Risk Managment: Freeport-McMoRan's Gold-Dominated Depository Shares

In 1993 and early 1994, Freeport McMoRan Copper and Gold (FCX), a mining company, issued two series of gold-denominated depositary shares to raise 430 million dollars for expansion of their mining capacity in Indonesia. We price the depositary shares using a term structure model for the forward rates implied by gold futures and we show that FCX successfully enhanced the credit quality of the issue. This credit enhancement is achieved because the effect of linking the payoff of the depositary shares to gold reduces default risk and is similar to conventional risk management. The building of financing and risk management, however, allows the firm to target hedging benefits only to the newly issued securities. The design of the security overcomes the asset substitution problem and credibly commits the firm to hedging. The depositary shares issued by FCX illustrate how firms can enhance credit quality through financial engineering without changing the existing priority ordering of their capital structure

The New Divisia Monetary Aggregates

This is the publisher's version, also available electronically from http://www.jstor.org/stable/183199

Field desorption ion source development for neutron generators

A new approach to deuterium ion sources for deuterium-tritium neutron generators is being developed. The source is based upon the field desorption of deuterium from the surfaces of metal tips. Field desorption studies of microfabricated field emitter tip arrays have been conducted for the first time. Maximum fields of 30 V/nm have been applied to the array tip surfaces to date, although achieving fields of 20 V/nm to possibly 25 V/nm is more typical. Both the desorption of atomic deuterium ions and the gas phase field ionization of molecular deuterium has been observed at fields of roughly 20 V/nm and 20-30 V/nm, respectively, at room temperature. The desorption of common surface adsorbates, such as hydrogen, carbon, water, and carbon monoxide is observed at fields exceeding ~10 V/nm. In vacuo heating of the arrays to temperatures of the order of 800 C can be effective in removing many of the surface contaminants observed