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Title: A demonstration of beam intensity modulation without loss of charge

Technical Report ·
DOI:https://doi.org/10.2172/132750· OSTI ID:132750

The large acceptance and the simplicity of H{sup {minus}} extraction makes practical unusual modes of cyclotron operation. RF equipment, initially installed for H{sup {minus}} extraction at TRIUMF, has been used to modulate the beam intensity at the extraction radius. This equipment consists of a 92 MHz, 150 kV cavity (AAC) and an RFD (11.5 MHz, 20 kV). The AAC augments the acceleration provided by the main 23 MHz, RF system; the RFD excites radial betatron oscillations. These devices may be operated at frequencies slightly different from their design multiple; their effect then beats with the main RF. In this mode the AAC, for example, alternately reduces the rate of acceleration, thus increasing the overlap of turns, then enhances it, sweeping the clustered turns onto a probe or foil. Operating the AAC or RFD in this manner gathers the bulk of the charge into peaks a few microseconds wide and spaced between 6 and 50 {micro}s. Changing the frequency offset alters the spacing. The peak to valley ratio was 23:1 and all beam was transmitted to the extraction radius.

Research Organization:
TRIUMF, Vancouver, BC (Canada)
Sponsoring Organization:
British Columbia Univ., Vancouver, BC (Canada). TRIUMF Facility
OSTI ID:
132750
Report Number(s):
TRI-PP-95-74; CONF-951039-1; ON: DE96002146; TRN: 96:000172
Resource Relation:
Conference: 14. international conference on cyclotrons and their applications, Cape Town (South Africa), 8-13 Oct 1995; Other Information: PBD: Sep 1995
Country of Publication:
United States
Language:
English