K.R. Chapman

The inverted sputter source

Abstract A sputter source in which the beam is extracted through the cesium ionizer works well and yields a bright beam of excellent emittance.

Microampere negative helium ions using potassium vapour exchange

Abstract Modification of the ion source of a model EN tandem Van de Graaff accelerator to utilise potassium vapour charge exchange has increased the negative helium ion currents to 2.0μA. Alpha particle beam currents used in experiments depend on the transmission through the machine and vary from 0.3 to 0.8 μA. The modified source has been used with potassium vapour exchange for continuous periods of up to three weeks. No upper time limit has been established. time limit has been established.

An ion source using lithium vapor exchange and giving several microamperes of 4He− or 3He−

Abstract An optical bench type ion source has been developed which uses lithium vapor exchange. The lithium reservoir holds a charge sufficient for over 350 h of operation and can be changed rapidly without disturbing the electrode alignment. The source has interchangeable exchange canals for operating with either lithium or hydrogen exchange. A coupling has been developed which enables the cooling lines to be coupled easily and without leakage problems. The use of freon as a coolant avoids previous problems with spillage of high vapor pressure coolant oil inside the vacuum system.

A second stripper for an EN or FN tandem accelerator

Abstract A second stripper has frequently been installed, part way down the high-energy acceleration tube, in an MP or other very large tandem to achieve a higher particle energy and charge state [1–3]. In an EN, FN or similar accelerator the space available in the dead section is very small, approximately 4″ in length and little more than the tube diameter transversely. The 4″ length must also accomodate the flexible bellows and vacuum seals that are necessary between the individual acceleration tubes. A stripper housing 22 foils 0.75″ diameter has been built and successfully installed, in this space, on the FN tandem accelerator at Florida State University. This accelerator has always operated with a 0.75″ diameter aperture in this position so no loss of beam transmission occurs.

Florida State University superconducting booster

Abstract A superconducting linear accelerator booster is to be added to the existing super FN tandem Van de Graaff accelerator installation at Florida State University to achieve an effective 12 MV additional acceleration voltage. A description of this booster, the tandem modifications to accommodate it and the present status of this project are presented.

Mounting of large stripper foils for use in the terminal of an electrostatic accelerator

Abstract A method of mounting stripper foils is proposed using a high transmission tungsten grid. This enables the foil to be subdivided into a large number of independent foils, failure of any one of which does not affect the rest. It is thus possible to use a large foil moved across the beam to obtain a very long life. Test results and a prototype mechanism to exploit this are described.

Production of 10B and 11B negative ion beams with a sputter source

Abstract A method for producing intense negative 10B and 11B beams with a sputter source for use by Tandem Van de Graaff accelerators is described.

Status of the Florida State University superconducting linear accelerator

Abstract The Florida State University Superconducting Linac has completed its first year of operation. The accelerator consists of 14 independently phased niobium (explosively bonded to copper), superconducting, rf cavities, injected by a FN tandem Van de Graaff. The history of the project, its present status and recent developments are outlined.

The Florida State University post accelerator — Progress report☆

Abstract The construction of the cryogenic linac post accelerator for the FSU tandem is proceeding well. Phase 1 and phase 2 are nearing completion and funding is expected this year to enable us to proceed into phase 3. Development of the tandem in preparation for the linac and the present state of the linac installation are described. A lithium polarized source is being built and the present state of this project is also given.

Comparative tests of the production of positive helium ions using a duoplasmatron with three alternative aperture arrangements

Abstract The production of negative helium ions by a charge exchange source requires an optimum positive beam to be extracted from the duoplasmatron and focused through the exchange region if maximum negative currents are to be produced. Comparative tests are described for three aperture arrangements to determine the positive ion current obtainable and typical parameters for operation.