Dr. Abdul Ahad

51 Pages·2010·4.29 MB·English

AAnn OOvveerrvviieeww ooff 55MMVV
PPeelllleettrroonn AAcccceelleerraattoorr aatt
NNCCPP
DDrr.. AAbbdduull AAhhaadd
CCoonntteennttss
• Electrostatic Accelerators
• 5UDH-2 Pelletron at NCP
– introduction
– Control System
– Ion Sources
– RC43 Setup
– RS61 Setup
• Applications (Ion Beam Analysis)
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
•• TTrruuee DDCC 110000%% dduuttyy ccyyccllee
•• LLooww EEnneerrggyy SSpprreeaadd 110000ee VV ttoo ffeeww KKeeVV
((11 MMeeVV ttoo 110000’’ss MMeeVV))
•• CCuurrrreenntt nnaannoo ttoo mmiiccrroo aammpp
•• AAllll MMaasssseess ((MMaassss iinnddeeppeennddeenntt))
33
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
Single Ended
• Higher Currents
• Ne, Ar, Xe
• Less energy spread (microprobes)
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
Tandem
• Source, etc. outside accelerator tank
• No molecular interferences - He++ vs. H2+
• Flexibility – Multiple sources
• Easy to upgrade
• Higher E for Vt, especially for heavy ions
THE NCP 5UDH-2 IS A TANDEM
66
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
Belt Charging system
Current transported by belt
Characteristics of Ideal Belt
- high resistivity
- little stretch
- moisture resistant
- smooth surface
- sufficient mechanical strength
• Dust Generation
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
• Pelletron charging System By NEC (1960)
• Metal cylinders with rounded ends joined by nylon
• Move at at bout 15 m/s
• Delivers charging currents of 100 - 200 µA
• motors are supported on movable platforms which
are counterweighted, automatically providing proper
chain tension
EElleeccttrroossttaattiicc AAcccceelleerraattoorrss
Pelletron Chain
• Spark damage well
protected.
• Better voltage stability.
- High efficiency.
- Insensitive to moisture.
- Long life (50,000 hours).
- Simple and reliable.
- Go to over 30 MV